@sparky8 another important thing to know :
If you see a toot of a user of another instance  in your timeline and you click on the username to see his/her/its toots, keep in mind, that you can only see the things your instance knows of the user. To see everything, it's the best to click on the avatar to see the original profile on his/her/its instance.
@sumomi you've been very helpful, thank you. I'm just having a glance of things for now. But I'll be sure to ask you if there's anything I need help with.
One of the first Mastodon instances, there is no specific topic we're into, just enjoy your time!