Can some help me get into this Harry Potter group on Facebook?

[Gumi]

Maybe you were banned for a reason, like if one of the admins had something against you and didn't want you joining the group or something. :/
But you do realize that in order to add you to a group, other people have to add you as a friend on Facebook first. You can't just add random strangers to a closed group. So get a friend to add you to the group, unless you want random strangers adding you and looking through your timeline... :/