Follow these steps to add a product or service:
- Click the Main Menu.
 	- Go to the Inventory tab.
 	- Select the Bills module.
 	- Click +Add Bill button.
 	- Fill in all the mandatory information.
 	- Go to the Item Details block.
 	- Click Add row.
 	- Select Products or Services.
 	- Select an item from the list of all items related to the linked Purchase Orders.
 	- Click Add Selected.
 	- Click Save.
 
To know more about Bills, click 
here.