Ooops..., I feel I am unable to find a solution which must have been explained in the help file or the forum, but I can't:
I have a few new users and I want to set their access rights, means I want to assign specific profiles to acces specific forums.
I did that before but can't remember
I think you want Admin > Members > Membergroups > Add membergroup.
No, I have my membergroups defined. I want to assign members to that group.
you can do it from their profile, under account settings.
Thanks, that was what I was looking for
:)