Binding instance of class to JPA

I have a loop which grabs meetings from a (Oracle) table and adds them to a calendar. Each calender event points to a meeting instance.

When you click on the calendar event, i open a meeting_details window, displaying the contents of the fields of the class instance to form fields.

What is the best way to persist any changes made to the form (instance of the class) back to the DB? If i use JPA, i cannot pass this instance of the class alone?