Welcome to how to make a Haunted Hallway!
Step 1: Research and Getting Started
First you have to research ideas and then gather a few items from your own file library of photos or a few quick searches online. I only used a few photos which I then put together in various ways to make my photo. During this step I will also work on my background picture.
After the research part it is just a matter of getting the photo to look like you want it to. After loading the picture into Photoshop, I immediately create a copy of the background layer so I don't mess up the original. This can be found in the bottom-right of the Photoshop window.
For my hallway, I decided to get rid of the ceiling light and smoke detector by using the simple "Healing Brush" tool. I simply ALT-clicked on the ceiling nearest the objects and then left mouse-clicked over the objects using "Replace" from the drop-down bar underneath the MENU bar at the top of the Photoshop workplace. When I feel that I have covered enough, I switch the drop-down bar back to "Normal" and this allows me to blend the surroundings very quickly and easily.
After this I used a series of the polygon-lasso tool and my favorite (the healing brush) to make the blinds line up more natural and look like they belong to the picture.
To finish up the mood section, I then go back to Brightness/Contrast and both darken the picture and slightly decrease the contrast. Now my hallway and home is dimmer and I'm ready to go onto the next step.
Then I went to The MENU bar and clicked on Image > Adjustments > Levels... which brings up another window. I just moved the dark marker at the bottom left of the graph to the right a little, bringing out some of the darker undertones of the picture.
Next I went to Image > Adjustments > Brightness/Contrast and moved the "Contrast" marker to the right just a tad. I like to do this as it clears up some slightly dull pixels the picture may contain without me having to mess with the colors directly.
Now it's time to set the mood a little better. I open the picture of the Blinds in another window tab and using the Polygon-Lasso Tool, quickly make a rectangle of the half of the blinds in the picture. Then I copy the selection (you can find that under Edit on the Menu bar) and paste into the hallway picture. Here I hold down the CTRL key while clicking and dragging and make a copy of the blinds. I then took the first layer of blinds and used the arrow pointer to move it to desired location and then went to Edit > Free Transform and rotated it until it was straight enough to my liking. Then I went back to Edit > Transform > Warp and used different points of the Warp transform tool to make the blind fit the window.