How to make a FPS Character Crouch and go prone?

i have no idea how to do this but i was thinking of some way of having it whe you click "C" the camera moves down and when you click "X" it move down even more and when you hit "SPACE" you either jump or go back to normal position.

As a start, have a look at:

Keyboard input in Unity: http://unity3d.com/support/documentation/ScriptReference/Input.GetKeyDown.html

Transforms: http://unity3d.com/support/documentation/Manual/Transforms.html

Scripting in general: http://unity3d.com/support/documentation/ScriptReference/index.html

Hope that helps. For the basic concepts of Unity, have a look at the manual: http://unity3d.com/support/documentation/Manual/index.html