Im trying to make a FPS game thats 3D can anyone help me make it 3D?

Define 3D…… Like are you trying to make a Doom like raycaster game? I assume you meant that as you said FPS game in 3D. If so then Griffpatch has made a tutorial on raycasting for your 3D like maze levels.

You can't make a scratch game 3D just like that… it is very hard.. unless you follow a step by step tutorial

What kind of 3D? Here are some types that you might like:

Raycaster: Maze-like 3D, camera is inside it
Pros: Quite simple and easy (especially sprite based)
Cons: Can only rotate camera left/right, no up/down looking or movement

Clone-based 3D: 3D world with movement and camera rotation in all directions
Pros: Lots of capabilities
Cons: Hard to code