To import products you first need to create a properly formatted import file. Each line in the file represents one product that you want to add/modify. You upload this file to your site. Each product must have a unique id to be uploaded.
Click the import/export link on the main store manager page.
Click the data transfer formats link.
Review the product import file format.
Create an import file using the same format as the example.
Click the "product catalog" link in the import section.
Click the browse button and locate the import file on your computer.
Click the upload button.
Review the uploaded data to verify that it is in the correct format.