Well we know one thing for sure, definitely don't do what got you there in the first place. Being in detention is a form of punishment, you should reflect on what you did wrong in order to change and do right.
Every school has a different set of rules for detention. Some common ones are:
1. No talking
2. No Electronic devices (Cellphones, MP3, etc)
3. Do something constructive with your time (Homework, Study, etc)
and most of all, Don't act out even if you were wrongly put in Detention. Most schools will punish you with BIC (Behavior Intervention or InSchool Suspension as it was once called), or worse Suspension.
Dr.GooberPlan