No worries man, it's a definite change from how the internet currently exists (i'll make a landing page explaining all these in more detail in the coming days)

The first link, !canvas@toast.ooo, will open up the community (the Lemmy equivalent of Reddit's "subreddits"). Being subscribed to that community will allow posts to the community to show up in your home feed

Matrix

Matrix is a chat protocol that is a federated live chat system, the Matrix protocol is not ActivityPub (what Lemmy, Mastodon and others run on) it runs on it's own protocol. The most popular client for Matrix is Element. You can host your own homeserver using Synapse, but it's highly recommended to use their main instance (matrix.org -- it's also the default option when you open Element in browser).

Matrix is setup in a way that you don't have to worry about missing old messages when you are on a new instance. When you join a new room ("channel") in Matrix, you will automatically be able to read old chat messages by backfilling old messages. Matrix also runs a very convenient website to share rooms with other people (matrix.to -- which is linked in my original comment) that will open a list of apps to open the room with (no vendor lock in).

Matrix is designed in a way were it doesn't matter what instance you are registered under. No matter the instance, you'll be able to read the chat, history and participate in live conversation.

Hopefully this cleaned some stuff up for you and like I said at the start of the post, I'll be making a landing page also explaining this stuff to help other people navigate this as well :)

(cc others in this thread: @Psythik@lemm.ee & @AndreTelevise@lemmy.world )