I will:
Access "File Management Centre" under the Seller Tools section.
Go "Upload Inventory" link and download the eBay Inventory Template.
Fill in the template with the required fields. These include fields for Site ID, Selling format, Title, Description, Category, Quantity, Duration,
and Location.
Save the template containing all your new or modified inventory, in .csv format.
Browse to select the file I saved, or enter the file path.
Upload Inventory