Do a lot of reading. Get a cyber informations systems basics overview on your own self-teaching before you try to understand it all.
Stay away from session and matrix. Signal, Nostr, SimpleX (nvm if you use Apple products) and the like are okay, but they are all hobbyist influencable products besides Signal which gets fat government grants and just happens to use the same encryption standards as all other huge name E2EE tools.
Stuff is fun to learn on, but get a good VPN (debates about.... mullvad, ivpn, cryptostorm seem okay). here's something fun for you and free: https://www.thc.org/segfault/