TYVM, Ronnie! Sorry for the delay in saying so, I didn't notice your comment when it was added.
Beginning is the hardest part. In the most basic terms, there's first a container, some "dirt" to fill it, some plants to decorate, maybe aquarium gravel to sprinkle on top, or something else you prefer. Then the scene, which changes often on mine. I've put newer pics in one or more other discussions on this mini gardening forum, which you can look through to see how it's changed if you want. The plastic dinos are so silly, I think they might be my fav part. Kind of a spoof of the ones with fairies.
The junkyard is just what it looks like, matchbox/hot wheels that were damaged or beat-up looking, made more so by hitting them with a hammer & scratching them up by rubbing them on the sidewalk & with an emery board. Burying them in the ground over winter would probably add a lot of "realism" to them. If you have tons of those little cars like we do, maybe do some now, bury some to trade or add later? Kids have awesome imaginations, I would let 'em use 'em, not give too much direction or preconceived notions.
If you do a web image search, you'll find more mini gardens than you have time to look at. That's how I got the junkyard idea. I was lost until I saw someone else's. Then I knew what I wanted to do. I still want to make a scene of gold prospecting/panning along a tiny creek (dry creek bed,) but need to find the right cacti for it. Got the idea for that from a bag of tiny gravel painted gold that I found on clearance at WM a couple yrs ago. I'm sure that's what it's made for, right? What else could it be...? LOL!