How to make path on picture?

Hi, I want to load a picture.
Then the character must be able to walk on a certain part of the picture.
Like they did in Final Fantasy 9. They have pre rendered images and the 3d characters walk on a certain predefined path.

How do i do that? should i edit the picture in some software like 3dmax or should i code it in maya?

if you pre-render your scenes in a 3d-editor. you can simply export the scene to an egg, with camera and floor geometry.
all you have to do in code, is to position the camera, and set up collision detection with the floor (the collision geometry will be invisible).

if you want to re-use already existing images, you have to reconstruct camera angle and walk-able areas. that’s a bit trickier. but there are a bunch of tools out there that can help you with the 3d reconstruction from a 2d image.