Hi sedric... sorry mate, just didnt have time to go over this any better. We are doing one for the VIP are that will use projection instead that will give correct results instead of simply adding the texture to the material and plonking on.
But this should get you started and using the sculpt tool
1. Make a nurbs plane - make sure you have (under makeNurbPlane1) that patches U and V are set for around 10.
2. Now go to edit nurbs - sculpt surfaces tool and adjust the "stamp profile" in the radious to your desired settings - just put them both on about 2.3 for testing, (my plane was the size of the grid) - change sculpt varibles so it only pushes and pulls in the "y axis"
3. Now pull and push to create a terrain look.
4. Now go to your hyershade and drag a lambert material from the left side to the work area
5. Now double click the material and on the right side of colour you will see a little button - point this to file and then to your desired texture.. I created a little one in deep paint 3d.
6. then just assign your material to the terrain plane
Hope this helps get you started, just didnt have the time to do a full on tutorial at this point.