No problem, what do you want to know? If you are here, it means that you already understand how federation works, i.e. you need to find a service provider/server on which to create your account, there are several sites to help you with that:

• https://joinjabber.org/

• https://providers.xmpp.net/#providers

then you'll end-up with a username like nick@server.tld and the password of your chosing, just like email, just like mastodon/lemmy. You will then log into using a client of your choice, and here as well you have plenty of choice: https://xmpp.org/getting-started/

If you are more of a power-user, I recommend Gajim, if you are on Android, Conversations/Cheogram are safe choices, if you are on i/macOS, siskin/beagleIM are decent, etc