You can be a strong rider able to hold high speeds or ride long distances, but there are specific skills necessary to ride in a group. I could probably fill a page with tips, but I would suggest a couple of things. Find a good group that's no drop and rides at a doable speed. Keep yourself near the front and following the group's accelerations. Look up the road, anticipating changes in speeds or upcoming traffic light. Above all else, ask questions and try to keep yourself from being discouraged. Good luck and don't be afraid to get out there. The more you show up, the better group rider will you become.