You can add products by using the CSV import file, or you can manually add them one by one by clicking the "Add Product" link in the Products settings area.
SKU: Optional inventory/product number. Dashes and alpha-numeric characters are acceptable. Using other characters may cause issues with product feeds and imports/exports.
GTIN: Global Trade Item Number. This value is currently only used for product feeds. Optional. Can be set to UPC, EAN, JAN or ISBN.
MPN: Manufacturer Part Number. This value is currently only used for product feeds. Optional. Alphanumeric characters..
Title: Product title. This should be alpha numeric. Though other characters are allowed, it is strongly advised that quotation marks, apostrophes and parentheses are avoided. This is especially true if you plan on using the product feeds features or importing/exporting via CSV file.
Main Category: This is the main/parent category your product will be displayed in. If a main category has been assigned, you do not need to add it again in the "Categories" tab (That should be used for additional/other categories or subcategories the product should be displayed in).
Short Description: Overview for the product. This overview will be displayed in search results as well as the product list. If in TEXT mode all HTML will be stripped when displayed.
Full Description: Details for the product. These details will be displayed on the product page only. If in TEXT mode all HTML will be stripped when displayed.