Steps to add new Product/Service:
Go to Items Section -> Product/Services.
Click on New Product Button.
Add the basic details like Name/unit of measurement.
Select "Yes" on enable inventory for this Product, if you are maintaining stock for the same.
Add HSN/SAC as per Product/Service/description and other if necessary.
Select the appropriate option:
I sell this product: If you are only selling the product
I Purchase this product: If you are only purchasing the product
Both: If it you both selling and purchasing the product.
Note: Once you create a product it cannot be edited to service and vice versa.