Simply get on the back, stay there, pay attention, and try to hang on. Get used to how it moves the first couple of times. As people rotate through just open up a gap in front of you and tell them to pull in.

Any decent line is ok with this. But, they hate it when the newb jumps in trying to be somebody and screws everything up. Watch, learn, and don't let a gap get you dropped if at all possible.

Have fun, and ask questions before and after the ride. Good luck!