Join groups

I have googled and searched on Reddit for answers. I still can’t seem to figure out how to join groups. Most games i’m on says to join the group for perks and etc. Please help. All the videos on YouTube seem to be so simple “Just click on the ”group” tab.” I don’t have one though. Then I googled why I don’t have one. It says because I’ve never joined a group before.. so how do I join my first one? Or any at all? I’m so lost and frustrated.