How to add new Shipper:
1) Under "Products" menu on left side of builder
2) Select "More"
3) Double click "Shippers"
4) Click "+" icon at the bottom of the builder to add new shipper
5) select from the list provided
6) Here you can use your login information to connect to the shipper, and rename it for internal use only.
Make sure to connect to Shipping Method before publishing.