How do I pay for my shipping Labels

Purchasing labels will use your credit balance. You can top up your credit balance by going to the Account Credit page and depositing any amount you wish. You can use this balance for a number of things such as Cart Saver, Offline Checkouts and more...

How do I pass this cost to the customer?

There are many ways in which you can pass the cost on. The main methods would be to put the prices of your products up slightly so that your customers would pay the shipping when purchasing products, and to create shipping rules that charged a fee to your customer that changed on the various weights of your customers' orders.