Sure thing, thanks. You got a great deal on them!
The base is a painting panel I got from art store, I just painted it black. I sculpted the "ground" from Das terracotta air-hardening clay. I like using the Das clay because it's fairly inexpensive, easy and kind of clean to use.... I added some rocks and other debris while it was still pliable. And pressed in the vehicle to make footprints... Then painted it a dark brownish color when it was fully hardened. Then I mixed white glue 50/50 with water and painted it on the surface so that the grass stick to it. It's pretty simple. I wanted to add more detail to the base, but part of my mission for this was to not spend any additional money and use what I had on hand. Also I wanted the base to accent the vehicle, not overpower it, hence it being a simple landscape...
You could make your groundwork from sculpted foam, Celluclay, plaster almost anything. Plaster can be messy though.
Added HO scale static grass/trees, etc. I've done a lot of dios and built a model railroad one time long ago. After it was all finished, I airbrushed the dark brown paint around the edges and footprints to make shadows....
When I built architectural models, we used spray adhesive for ground scenery. It's kind of hard to control though. You can also water down white glue enough to use in a spray bottle.
I thought I had taken pics of adding the additional detail but I can't seem to find them. The leg armor skirts as they are in the kit are pretty naked looking.