rosenrot:
I know almost nothing about tabletop games so I guess I fall into the "free-form" category?
I'll just chime in here to point out that many of the people who run games here are perfectly willing to teach you the rules if you ask for that. So the fact that you haven't gotten familiar with those kinds of games
yet definitely does not need to be an obstacle if you find something that looks interesting but uses a system you don't know.
And as a side note, it's also worth pointing out that there's a pretty broad spectrum between "totally free-form" and "rules for everything," and if you experiment you might find that your preference is somewhere in between.