To set up class in quickbooks, you need to activate class tracking.
On the Quickbooks menu, click edit and select Preference
A Quickbooks preference window pops up
Select Company Preferences
Tick Use class tracking for transactions and prompt Quickbooks to assign classes if you wish.
Click Ok to activate.
To add and track class in Quickbooks
Click List on the Quickbooks menu and select Class List
When you click Class List, a class window pops up.
At the bottom left, click Class and select New
Enter the description of your class tracking in Quickbooks and click Ok.