To get the most out of forums on your course, participate fully. It can make a big difference to your enjoyment and understanding of the course.
This means
The only way to do it is to have a go, make mistakes and enjoy yourself in the process. In the end, the more you put in, the more you will get out.
If you are asked to do particular things in the forum, get on and do them! Making a commitment is really crucial. Once you feel it is 'your' forum you will want it to work well, and everything else will tend to follow.
If you can't be very active, let people know:
"sorry I can't be around for a while, but I'll do what I can when I get back".