How does tumblr work? How do I use it?

[Amellia]

I really want to get into tumblr but I have no idea how, it's so confusing to me, I created an account. But then it asked me what "blogs" I want to follow, first of all I don't even know what a blog is? and second of all I have no idea!!! Should I follow some fandom ones? and then some "blogs" take you to a whole other place? I don't want to post pictures of me or anything I just want to "follow" if thats what you do. I am super confused about what to do. What is tumblr even about? It seems like it's really cool and everyone uses it, but I don't get it! I'm not old either, I'm a teenager and I feel so alone.
I use Facebook, outlook, and youtube.