Where can I edit the Postage / Shipping Label for Magento?

Is it in the back end? Or through the FTP?

Just need to edit the layout of the invoice that gets sent to the customer that's all.

Thanks for your help

Where can I edit the Postage / Shipping Label for Magento?

Is it in the back end? Or through the FTP?

Just need to edit the layout of the invoice that gets sent to the customer.