To add a variant to a Shopify product follow these steps:

1. Open the Airtable sheet where product variants are being synced to with Shopify
2. Add a new row for your variant, and give it a name
3. If you have more than one variant for the product, make sure that you fill out the columns where the Option 1, Option 2, and Option 3 values are stored, depending on how your variants are differentiated
4. Initiate the Airtable to Shopify sync. Monitor the Sync Error column just in case there are issues with the new variant data