Originally Posted by ErikChou
Want to know how to join groups
You leave us guessing----do you mean:
user groups---eg a local Linux users group?
a social group, book club, etc.?
something like AA?
If--as guessed above--you're talking about groups on a Linux system, then note that users do not join groups----it's the other way around: groups are added to users.
If Google is not working for you, then here is a Linux "power tool"---in a terminal, enter "man -k group"