Fun tutorial, how to transform rope into a snake. We will need photoshop, and sample images with a snake and a rope. I'm using Adobe Photoshop, but you can use any photoshop software (you can use open source free GIMP).

Step 1: Open File

In Photoshop, choose File→Open.

Navigate to the folder that contains your file, select file and click Open.

Step 2: Import Snake Image

Duplicate layer (optional) CTRL + J (Cmd on the Mac).

Import snake image: file > place embedded > select image > place.

Place the snake image so it's easy to access. At the end of the tutorial we going to delete it anyway.

Step 3: Make a Selection

Make sure the snake layer is selected, navigate to toolbar and select lasso tool. Select a fragment of snake > CTRL + C (copy) > CTRL + V (paste) > CTRL + T (select).

Click and drag the fragment on the rope.

Step 4: Add Layer Mask

Resize it, so it fits the rope by holding SHIFT and dragging the dots.

Select layer mask from the Layer panel. Use brush tool and foreground color black to mask areas, foreground color white to unmask.

Step 5: Fit the Shape With Warp

Right click on the snake fragment and select warp and enable grid in the upper toolbar (optional). Drag control points to adjust the shape. To undo unwanted changes use CTRL + Z.

Press enter.

Step 6: Copy Paste and Repeat

CTRL + J to make a copy of the top layer, then drag the new layer to cover next part of the rope. Repeat the process until the rope is fully covered.

Step 7: Add Shadows and Highlights

Add new layer for shadows and new layer for highlights. Use brush with reduced exposure and opacity (upper toolbar), select layer blend mode Soft Light.

Step 8: Adjust Tonality With Curves and Vibrance

Select Curves from Layers panel, adjust graph to your image needs. Then add Vibrance adjustment layer and use sliders to make the image stand out. Be careful not to over do saturation though.