Animating a roller skating girl

Start by opening an image of a girl with roller skates.

Create selection of the girl using polygon lasso tool or pen tool.

Press Ctrl+Shift+J to cut paste the selection in a new layer. Hide the layer.
Select the background layer. Cone the deleted area using clone stamp tool.
Unhide the girl layer. Duplicate the layer.
Create selection of both the legs individually using polygon lasso tool. Press Ctrl+Shift+J to cut paste each leg in a new layer.

Interchange the position of both the legs i.e. right leg below left thigh and vice versa.
Select and merge both legs along with the upper half of the body layer.

 

Select original pose layer. Duplicate, scale down and place as shown.
Now sequentially create duplicates of original pose layer and swapped leg layer and scale up each duplicate. Move duplicate towards right edge of the file as shown.
Open animation window. For the first frame hide all duplicates. Keep duplicating frame in animation window and unhide the duplicate layers and hiding the previous pose.

 

Press Ctrl+Alt+Shift+S to save an optimized animated GIF.