I'm going to have a go at explaining how to use Lemmy in a simple way.

You only need one good instance to access all of Lemmy, but it can be nice to have an alternate in case the primary goes offline for some reason. For best network performance try instances in your region. You can sort instances by country here; https://the-federation.info/platform/73 When you find one that works well for you, make it your regular login instance.

Once you find a home instance, go to lemmyverse.net/communities to find communities of interest. Copy the link on lemmyverse by clicking on it (i.e. !technology@lemmy.ml) then paste into the search box on the communities page in Lemmy. Click on the listing from the search results then select the Subscribe button. It may show "Pending" for a short time then turn to "Joined". If it doesn't change right away don't worry about it. You're in even though it may look stuck.

The front page view defaults to Local, you don't want that. Go to your profile settings and set the view to "Subscribed" (you could use "All", but your front page will have a ton of junk you don't want to see).

That's it, you're ready to use Lemmy. Of course this is for desktop browser. I'm not familiar with the Liftoff mobile app for Lemmy so I don't have directions for that.

Additional; there's other things to know about such as federation which involves blocked and linked instances, but to start just avoid communities on beehaw.org since that instance is one known to block other legit instances. If there is a community on beehaw.org you really want to interact with, you have to check your login instance is not blocked there. There's a procedure for that, but I'll spare you the information overload.

Okay, hope that helps and enjoy!