Preliminary hearing for Shoplifting?

My friend was caught shoplifting about two weeks ago at wal-mart. The total cost was around $40 and this is her first offense and she's 17. The police were called but only because her mom could not pick her up and the police had to be there so she could be released to another family member. She's worried herself sick about this and she's learned her lesson. She received a letter saying she has to go to court this week for a Preliminary Hearing. She wants to know what is going to happen at this Preliminary Hearing, and what's going to happen after the Preliminary Hearing??