How to heal as a resto druid
You are going to want a good healing addon, my favorite is healbot. Once you get it installed setup your left, right, and middle click buttons to all of your heals.
When healing as a druid it is important to keep the tank alive so you should always have your HoTs up on your tank. Even more important than keeping your tank alive is keeping yourself alive, if your tank dies you can still rez them
Keeping everyone alive
When DPS start to lose health throw a rejuvenation on them and they will usually heal back up to full. Resto druids have two forms of CC, roots and cyclone. It isn't expected of healers to CC but it can help keep everyone alive.