i cant seem 2 find out how 2 get the real look on the base of the diorama can anyone help me thanks

I've made ground using a mix of pre-bagged shredded paper mache (available at arts/crafts stores), water, elmer's glue, brown acrylic paint and real dirt. Once I get a workable consistency, I slap it down on the base (the glue in the mix helps is adhere) and shape it. While it is still wet, I sprinkle it with fine real dirt and static grass and whatever else (rocks, etc.) I want. Before it dries you can also press in tire tracks.

You can use cork board, break it up into pieces then glue to surface of base itself. This allows for small hillocks, flat areas etc... You can cover this with the Celluclay mixture, sand, railroad ballast or sifted soil from your yard (no worms, please). Score the surface of the wood base to help mixture adhere to surface better. I use Elmer's white glue and a touch of laundry liquid then add sand etc and paint for tint then mix/stir it up to a mush like thickness and apply with plastic knife or whatnot.
Make sure you seal the wood base first, as the moisture of the celluclay mix can warp the wood.
You can paint or stain the wood base prior to adding glue or wait until the celluclay is dried in a few days. Your call.
As the celluclay hardens, you can place your vehicle or spare tracks or spare tires into the mix for ruts and tracks, or footprints if figures are in the dio. You can add garden variety stones, make fences posts out of balsa what ever you want. Practice on some scrap wood first if you have expensive bases.
Experiment and have fun, that is the basic idea. Good luck, amigo.
Ironmike