You can find detailed instructions on how to sync your own Shopify store to usastrong.IO here. 

The benefits of syncing your Shopify are: 

• You will be able to import the products from your store
• The inventory on usastrong.IO and your Shopify will be synced
• Orders for connected products will be created in your Shopify store automatically
• All orders created by usastrong.IO will have the following customer email structure: {orderid}+email+marketplace@usastrong.io
• You will see customer information in order’s Shipping details
• You can continue fulfilling the order from your Shopify admin, usastrong.IO will pick up the tracking ID automatically