Hi!
Sounds like you find yourself on a bad instance! Like Lemmy, you can sign up on many different websites that run Mastodon. The good ones are very well moderated. :)
What are you looking for in the platform? Which topics do you want to discuss, and in which languages? I'm sure folks here can help you find a good instance for your needs.
Other than that, it is based a lot around following people and hashtags. But finding an instance run by someone you can trust is the first step! :)