I know it may be a lot of users’ first time using something that is decentralized like this. As I’ve been a Fediverse user for some time, I had been waiting for a big migration like this to happen as it usually happens with Twitter every now and again. Welcome to Fedi, hope you enjoy your stay!
There are some websites that can help you:
https://lemmyverse.net/ https://browse.toast.ooo/communities
Take a look at this post too: https://mander.xyz/post/859785