Great start there, Clone Hunter! I would agree with some of the earlier comments about taking this one to the next level. Right now, though, it looks very much like something we might get from Hasbro, so in that respect you're spot on.
If this was my dio, I'd do the following:
Create a base for your base.
Get a cut of plywood large enough to leave you a few inches on all sides outside the base. Prime the surface of the plywood. Let the primer cure. Glue the playset to the plywood base. Let that dry so the playset will not shift about on you. apply a thick layer of glue to all remaining areas of the plywood not covered by the base. Take common beach sand and rub it into the glue - it's OK if this gets a little clumpy or messy. Let that dry really well. Glue in larger rocks around the playset, with some actually leaning up against it. This will incorporate the plastic playset into your diorama.
When done, remove the non-earthen elements of the playset (guns, power packs, metal shelter). Take the entire set - plywood, playset and all - and paint all recessed areas with a wash of black. Then dust coat the entire set with a lighter shade of brown than the one you used on the playset, with less attention to the random rocks you have scattered and more attention to your sandy areas. This will make it look less like the beach, and will also dust your playset in a color that will make it blend better with the new diorama area.
Finally, reattach the non-earthen elements (perhaps after weathering) and add a few items of vegetation if you want. This is also the time to put in props (abandonned blasters, droid pieces, etc)
I did something very similar to this in my previous hobby as a Gundam model builder. Here is one of the only pics I still have of it after selling much of my Gundam stuff...
If you stick to trying to blend the playset with your new plywood base, you'll end up with something really special and unique to your collection.
Nice job so far, and good luck as you move forward!