I've always played solo casual games, but after watching Summoning Salt and SmallAnt1, etc, as long as I can find a game I enjoy that I can play here (I haven't yet) I hope to contribute to the community.

Well, welcome to the site!

We've got a FAQ here if it helps at all: https://www.speedrun.com/speedrunning/thread/pt010

Since you're looking to find something to run, we've got a thread where folks advertise their speedgames to try and build up their communities: https://www.speedrun.com/speedrunning/thread/hl23s