Setting up vendors for your products allows you to keep both your purchase orders and your inventory organized.
To create a vendor:
Click 'Inventory' in the left side menu
Select 'Products' from the dropdown
Navigate to the 'Vendors' tab at the top (purple)
Click the 'Add New' button on the right side of the screen (blue)
Detail of the tabs in Inventory > Products
Clicking the 'Add New' button will take you to the New Vendor section, where you'll be
able to add a vendor's name and contact information.
The new vendor screen
Note: you'll also need to have added all the locations your products are stored in, before you can add products to the inventory management tool.
Repeat this for all vendors you're supplied by before you start adding products to the inventory tool.