you need a software :
Dino / Profanity / gajim / pidgin etc...
then you need a server, because XMPP is a protocol, it's free to use so people run their own servers. I recommend using Creep.im (check their website)
After that, register using the app, and then you can start a chat with a person, if you have issue, switch to their server.
also one important thing, for security, in case you don't want your privacy to be visible to anyone. in case messages are stocked on the server you can :
Use OTR (Off the record) & encryption like OMEMO or PGP. This way if the message is stocked on the server, it'll be garbled mess. it's important to do so, and very easy to install, you just need to certify the fingerprints.
have a nice day, this might be intimidating, but just look step by step
I do not sell anything. I do not have a public Discord / Telegram. I will never ask anyone for money / refuse any deal via middleman. I will never deny to confirm my identity via PM before any deal. Stay safe, I have impersonators.
(-.-)Zzz...
https://youtu.be/EDVrTYW2l84