To connect your BigCommerce account to Sellbrite, navigate to Settings > Sales Channel Integrations > Connect a New Channel.
Scroll down to the "Shopping Carts" section of this page and click the "Connect" button for BigCommerce.
This will take you to the BigCommerce connection page. From here, click "Connect your account."
A pop-up window of the BigCommerce login page will appear. Enter your BigCommerce email address and password and log in.
Once you have done this, Sellbrite will connect to BigCommerce and automatically begin importing all of the products from your store.