I need more information. Do you not know if you were convicted of possession of alcohol previously?
This is a serious charge. It is a class 1 misdemeanor which means you can face up to a year in jail, pay a $500 fine, be given 50 hours of community service, and lose your license for a year. The penalty could be worse if you did have a previous conviction of the same charge.
The college could definitely find out about this incident.
I would definitely recommend you hire an attorney. This is something our firm can help you with.