In most jobs we are required to work in groups to perform tasks. This is often the case in the classrooms environments as well. Here are some resources that might be helpful moving your group work online.
Prof. Robert Morris at Niagara County Community College held a session on using groups in an online course:
Stephen Sturman at University of Buffalo
Developed a series of short videos on how to create group work in online courses
YouTube Video Series
SUNY Niagara Online Teaching Academy 