I've been meaning to try Mastodon for a long time (I was never really a Twiiter user). As others have said elsewhere though, I'm not sure where to start. Did you just download the app and join mastodon.social?
I did much less. Just went to mastodon.social in my browser and read what is there. I think you can create an account from there. You can also choose another instance to read and create the account from.
If you create an account, it may be worth looking into "starter packs", which are lists of accounts around specific topics to follow. That's an easy solution if you run into the "I don't know who to follow and there's no algorithm that'll tell me" problem.