1. One by one
2. In bulk, using a template.
1. One by one
Go to 1. Products and click 2.+:
Fill in the information and click Create; the * is mandatory:

For an error message received:

 
 verify if the product was entered under a different SKU/barcode: 1. search by SKU, 2. identify the differences, 3. Click the name to edit the product:

Replace the wrong information:

with the 1. correct one and click 2. Save:

Go to 1. Products and 2. Search the UPC to verify the correction was completed:

2. In bulk, using a template
Go to 1. Import Data and 2. Download the 3. Products template:

Open the template and fill in all the fields and Save the template:

Go to 1. Import Data and click 2. Upload File:

click 1. the Template and click 2 Open:

Depending on the size of the file your upload could take from a few seconds to a few minutes.
Refresh your browser if the status does not change.
For uploads with errors refer to: