Hi Michelle and welcome!
A great place to get ideas for Smith machine exercises is
Exrx.net. If you click on a muscle group, it will give you a huge list of exercises broken down by equipment type. Usually there are several listed for each muscle group that use the Smith machine. And it has those awesome little videos.
Personally I've done squats, lunges, shrugs, flat and inclined bench press, and close grip bench press on one, though I'm sure there are more exercises one can do. But I don't do squats on them any longer due to the stress placed on the knees.
As for leg exercises without machines, some basic ones would be squats, lunges, and step ups. You can use a BB or DBs with any of them. Have fun!