You have to get ticket from your manager and appear in the court in exact date/time with ticket.

 In the court, you have to pledge "Not Guilty" and Judge will assign you next court day.

 If you pledge "Guilty", in future you will have problem in your background check.  

 
In the next court date, again you have to  pledge "No Guilty. In this time you will have an opportunity to explain your situation to the Judge.

Explain him  that you did sell tobacco but you were in training... and it happened by mistake.... and assure him that it will not happen in future...

 
Most probably judge will put you in Probation for one year.

Don't repeat same mistake in probation period.  After probation period your case will be dismissed and it will not appear in your background check..

 

I think in the court they will not ask about your F1 status and you also don't have to mentioned

about it. They will just ask about your case ie. selling tobacco to minor.

 

If you like you can continue to work in the same store, it will not affect your case.

 

This is just my opinion. I hope it helps.