...and, if you're totally lost, or you have friends who are totally lost, this is a really short video that explains Mastodon in really simple terms. It's a good starting point:

You don't need to use the official Mastodon apps, they're not the best way to use Mastodon. The official apps only arrived last year, and they were intended as "Fisher Price My First Mastodon" things with a restricted set of features.
Third party apps have been around longer than official ones, and include way more features. You can sign in with the same account on all apps.
On Android try Tusky, Fedilab, Megalodon, Tooot
On iPhone/iPad, try Toot!, Ice Cubes, Ivory, Mona
I'm noticing a lot of "I'm bored of Mastodon, I'm going back to #Twitter" posts.
In case they are genuine, here's what I've found works:
⚫ try to post content, not complaints. People want to engage with you, not your gripes
⚫ try to learn. If you're putting in an effort to be part of the community, the community will welcome you
⚫ Try to avoid posting links to tweets, definitely don't cross-post. People want Mastodon content
⚫ Reply! Reply! Reply! Everyone wants to know someone's reading and considering their content, even you
⚫ Don't lurk. Many of us check for a filled out profile, avatars, and posts, before we follow someone back
⚫ Chill. It's a big new world that doesn't serve everything up to you
⚫ Avoid the trap of rebuilding Twitter here
Feel free to link this post to people struggling with Mastodon. It's what I've found works, and may not work for everyone