It's exciting that more and more PCC accounting students are finding early work at CPA firms before they've transferred to a university for more advanced accounting coursework. The challenge is that you might be on an "audit" team but haven't taken the auditing course that will fully prepare you for this process. Here are some resources to get you started!
Also, here's a series of auditing interview questions and possible answers to prepare you for an interview with a CPA firm.
Finally, here's the book PSU uses for their auditing course for an accounting degree. It looks like there are some inexpensive used loose-leaf options available.