Hey again Kerri -
You'll want to look for their information on lower-paced rides for beginners; they usually note the mph and that the group rides on local bike trails or short rides on quiet backroads at about 8-10 mph/social pace, and stays together, stops often and probably even takes time before riding to go over some basics - proper helmet placement, hand signals, riding safely, etc.
Remember that it's a great opportunity to practice and learn and that there will undoubtedly be other "wobbly" newbies too, so that you don't have to practice beforehand. Have fun!
Mary