You are probably charged with criminal mischief for damaging someone else's property. If you have never been in trouble before, you are most likely looking at a short probation sentence, a fine and a court order to pay restitution (to fix the window).
If you really have no prior criminal history, you should consider applying for the State's Pretrial Intervention (PTI) program. The terms of that program are pretty much the same as above, but if you successfully complete the program, your charge will be dismissed when you are all done. That is definitely the way to go if you are interested in keeping your record clean and/or sealing or expunging your arrest record.
If you have any specific questions, feel free to contact my law office and I can answer them for you.
Maximum penalty on a 2nd degree misdemeanor is 60 days in the county jail.
That said, if you've never been in trouble before your more than likely not going to get any jail time. Pretrial Intervention (PTI) may be available, contact an attorney or ask when you go to court on your case. This will result in the State dismissing charges against you upon successful completion of a program or class. If you want to just resolve it you more than likely can pay a fine and get a Withhold of Adjudication. Good Luck.