Please note, this can be done while adding a new product.

1. Select Products from the Store menu. 
2. Search for your product and click the Edit link next to the product name.
   
   
   
3. In the Tags section, enter a new tag, and then click the Add button.  
    
    
4. To select from a list of existing tags, click the Show existing tags link.
   
   • Click each tag you want to add to this product record.
     
5. Click the Update button.