For the old guide to set up discordfriends on matrix seematrix guide.
Matrix
Matrix has it's problems, but if you use good clients and set everything up correctly, it can be pretty good; and by using it over other messengers you will be supporting a better and more sovereign future for online communications, and the server and clients keep getting better. Matrix also has lots of support for bridging your accounts on other platforms so you can use a single app.
Homeservers
Matrix is a federated protocol, this means that people on different servers can easily communicate with people - this is one of it's gretest strengths. You can think of it like Email for instant messaging.
The first thing you will need to do is register on some server. I reccomend against using the default matrix.org for speed, ideological, and privacy reasons. If you want to use my server registration should be open soon at communion.quest. If it is not yet open and you would like an account, feel free to contact me. Here are some open servers I am aware of that work well and have a good record to my knowledge: Halogen Place,Joe's site,andmidov.pl(but the weirdo shit on midov.pl website really turns me away).
Clients
There are a lot of clients. I preferCinny;SchildiChat; and the default client,Element.
Communities
Sadly though the software has come a long way I am not aware of many quality communities on Matrix.Hack Liberty is a pretty good, active tech/privacy space andpol2 is my pet dead edgelord room.