Drums
If you're playing the drums for your group performance, you have the most important part because you are responsible for keeping everyone in time.
Your drum rhythm should be made up of 3 different parts:
1. The bass drum
2. The snare drum
3. The hi-hat cymbal
You should find a copy of the drum tab for your song, which looks like this (this can be easily found on the internet):
Hi-hat
Snare Drum
Bass Drum
These are the beats (or counts) you have in each bar. This will help you figure out what rhythm you need to play.
The drum tab above is for 1 full bar of a rock beat in 4/4 time. This is a common and fairly straightforward drum beat to begin with, so have a go at playing this first before you attempt the drum tab for your own song.
If your group doesn't have a drummer, or your drummer is away when you need to practice, have a go at using this online drum kit to loop a beat while you play: http://drumbit.pluraldev.com/