Simply hover over the product you wish to add and click "Add to Import List"
Then, visit your Import List
The product will then appear in your "Import List". Here, you can make changes to your product before it goes live in your store.
When you're ready, click "Add to Shopify". To add multiple items in bulk, select the checkbox on the top and click "Add Selected to Shopify"
Done! Your product will now appear in your Shopify store ready for sale.