I don't know if some of you have been answered in PMs or not-so here is just a blanket post to get some general answers. There is also a forum called Site Suggestions if you need a more detailed answer (but I hope this helps
Can't post a reply? Double check the upper right corner of your screen. Does it say "Welcome, *your screen name here*"? If not, you need to log in. Make sure you click the box for keeping you automatically logged in.
Want to join a User Group? Go into User CP (It's on the top blue bar on the far left), then down to Group Memberships. You will get a list of groups you can join, like the Divine Secret Sisterhood, SU! Demo forums, etc. Click on subscribe and you will be sent instructions.
Want to change your signature line or add an avatar? Again-go to User CP. The top of the list on the left will take you to 'Edit your signature' or 'Edit your avatar'. You can edit your public profile there as well.
Moderators for certain groups-
Orphaned demos-suthunheart (Marcia)
Hope that this is helpful!