Use the following steps to create a file for adding new products to your website.   

Go to: Interfaces > Import / Export Data

Use Tutorial: Export Inventory for Custom Products to Indie Commerce, WordPress, Shopify or Wix

Additional notes for Shopify users:

You can download and view a sample product CSV file to use as a template.

• The sample file contains an example product and a couple of variants. Your import file probably contains many more products and variants. If you use the sample file to create your own import file, then make sure that you remove all the example products.
  
  
• The sample file includes the Variant Inventory Qty column, which is only used for stores that have a single location. If you use multiple locations and you want to import or export inventory quantities, then use the inventory CSV file.

Source: https://help.shopify.com/en/manual/products/import-export/export-products