I want to make a good group that everyone will join! Though it's hard, and my biggest group(that I made) has only 7 people!

Please help!

Have some sort of theme for the group.

I want to but I don't know how to make a theme for it!

While a literal theme is nice, I believe he means a type of group.  If there's something just called "my group," no one will join.  (although there are some exceptions)  If you make a group, people need a reason for joining.  Like one for basketball, or baseball, etc.  Make sure you check to see that there isn't alreay a group with your theme.

Once it's started, give people a reason to stay.  Team matches, vote chess, tournaments, puzzles, and other stuff to do helps. 

Remember: be innovative!  If you want people to join, do something that no group has done before so that people would want to join.

i do...