you need to model a terrain then texture it or you could try
Visual Terrain Maker
You then need to make a script for it(.fpi) , here is a simple script template
;Entity Spec
;Header
desc =
;AI
aiinit = appear.fpi
aimain = default.fpi
aidestroy = disappear1.fpi
;Spawn
spawnmax = 0
spawndelay = 0
spawnqty = 0
;orientation
defaultstatic = 1
model =
offx = 0
offy = 0
offz = 0
rotx = 0
roty = 0
rotz = 0
;visualinfo
textured =
effect =
transparency =
Also dont forget that you need the texture as a dds in the same folder as the script , model and entitiebank screenie (This should be a BMP file) if you install
Visual Terrain Maker then the BMP , DDS and Model is of course already made but if you model it then its alot more advanced
Windows Vista,ATI Readon HD 4870,AMD Athlon 7750 64 Dual Core,4GB ram