I had drawn number of sketches of cats in various poses with pen and paper, that I wanted to incorporate into a Halloween drawing using Sketchbook Pro. When I was working on my drawing I realized that it would work much better as an animation. To that end, I composed the scene on one canvas but drew each component on a different layer so that I can hide and show the individual layers to create each frame. I then opened the frames in GIMP and created an animated GIF. Here are step-by-step instructions of the process.

Step 1: Drawing Cats

I had borrowed a "learning to draw" book from the library not too long ago and it was obvious that the author really liked cats. In one section of the book, I think he was discussing form, he had numerous little sketches of cat outlines. The cats were sitting, standing lying down in many different poses. I had a lot of fun drawing these simple cats sketches, and having my own cat model at home I had plenty of opportunity to practice. The great thing about drawing cats is that they have a very characteristic shape so that it doesn't take much detail to identify it as a cat. Just draw some ovals, circles, and little triangles and there you have a cat. In the images above you can see some basic starting points in green, then filled in more to give an outline (which is what I will be using for my animation). From here you can draw further details like the facial features and fur. These sketches are of course simple cartoon like drawings, if you want a realistic drawing that requires a bit more time and detail.

Step 2: Tracing and Colouring Cats

I sketched my cats with pencil and paper since I find it awkward to draw with a mouse. I then outlined it with ink and photographed it.
In Sketchbook Pro I opened up a new canvas. Flood filled the canvas with a dark grey. I added a new layer then selected add image to open the sketches that I had photographed.
I adjusted the two layers so that I can see the cats and be able to trace them and also be able to see the white ink that I was using.
I used the pencil tool, size 3.2 with white ink to trace each cat.
Once I had the outline for each cat I used a Copic Super Brush Nib tool to colour in the cats, I used the smudge brush to blend in the colour
With the hard eraser I cleaned up where I coloured outside of the lines. I then saved the file.

Step 3: Background

I went with a simple background for my scene. While adding the background colours I tried to create a horizon line so that it was darker in the sky and lighter on the ground. On a new layer I airbrushed some dark grey across the screen, the brush size was about as large as it would go.
I added a new layer and airbrushed some dark blue across the screen then use a large smudge brush to smudge the blue around.
On another new layer I used black on a large paint brush and layered some black paint on. I then smudged the black with a smudge brush to blend it in.
I adjusted the opacity of each of the background layers to get the look that I wanted.

Step 4: Moon

To make the moon, I started on a new layer and use the Synthetic Round Bristle Brush with a whitish colour and dabbed it on to the canvas.
On a new layer with a smaller, denser brush I added a lighter white to the centre area of the moon
On another layer I drew in some blotches of grey and blended it in with the smudge brush
I then added some white lines with a pencil for the craters on a new layer.

Step 5: Adding the Cats

Now that the background is ready it is time to bring in the cats. I added each cat on a different layer.
I went to the layer where I traced all of the cats. Grabbed the first cat with the lasso tool, copy and pasted in onto a new layer.
With the hard eraser tool I erased the original background so that I was only left with the white of the cat.
I repeated this with the three remaining cats and placing them where I wanted them to be in the scene.

Step 6: A Pumpkin

What is a Halloween scene without a pumpkin. I used a new layer for the pumpkin. I used the same paint brush I did for the moon but a smaller size and with a bright orange colour. I used the smudge brush to even out the colout
On a new layer I drew in some lines with a darker colour for the creases and blended them with a smudge brush
I then drew in the face of the pumpkin with black ink and the pencil tool on a new layer. I refined the shape of the pumpkin.

Step 7: Lightning Bug

For the little lightning bug I used a Synthetic Soft Round Brush, size 5.0 with a pale yellow colour. I used the pencil to make the hash marks indicating the bugs flight path.
I added each step of the bugs flight on a new layer.
When the bug reached the pumpkin, it disappeared inside and light up the pumpkin, I drew over the black cutout of the face and the opening at the top with the pale yellow colour.

Step 8: Happy Halloween

I continued the lightning bugs flight path into the sky where it then lights up some text
I used the text tool with the pale yellow to write out Happy Halloween
On another layer I wrote the same text in orange
I then added a burst of light using the airbrush with the pale yellow on another layer
I drew in paw prints with the pencil tool leading between the first and second cat image and the second and third cat image. I put these on separate layers.
When looking at the finished drawing I realized that the background seemed to large and the components too small. So I moved the moon lower and cropped the image so it is not so spread out.

Step 9: Layers and Saving

To make all of the frames in my animation I adjusted each layer in sequence using the opacity setting or just hiding the layer. To make this easier I labelled each layer properly and merged the background, moon and pumpkin layers since they will be constant. So for the first frame I only had the first cat showing at a reduced opacity so that it looks ghostly. I saved this as a JPEG file. For the next frame I increased the opacity of the cat and un-hid the first bug, then saved it. The next frame I adjusted the cat to full opacity removed the first bug and brought in the second bug, then saved the file. I continued this way for the whole scene saving fourteen JPEG files. I named each file in numerical order (1-14) so that it will be easier to load in order in GIMP.

Step 10: Making Animated GIF

To make the animated GIF I used Gimp 2. To Begin I went to the file menu and select Open as Layers
I selected files 1 through 14 using the shift key and clicked open.
This opened all 14 files though you only see the last one on top, they should be layered in order if you numbered them correctly
Go to the file menu again and click Save as. Change the file type to GIF, name the file and click Save.
This opens up a window that asks you whether to Flatten Image or Save as Animation. Select Save as Animation
and click Export
This opens another window that shows more saving options. I changed the delay frames to 1000 milliseconds and selected to use the delay for all frames. Click save.
Your animated GIF is now done, I usually view mine in a web browser.

Step 11: Video

I was disappointed by the quality of the GIF image, though I should have realized that Gif files are limited to 256 colours. I wanted a better quality animation so I made a video from it. I use Moviemaker which comes free with XP but if you have moved on from XP (I am using Windows 7) you can still download it and use it. I still use it because it is pretty simple to make movies with it. I won't go into detail of the process I just loaded each frame in order, adjusted the time duration of each frame to 1 second, I didn't add any transitions. I guess I could have incorporated audio, but I don't know what music would go with it.