To print out a FedEx shipping label go to FedEx website and search for create shipping label and there should be a page where you can order and pay for shipping for a package and then be able to print out a FedEx shipping label from your printer.
You'll need some paper that's made to create labels though that you can peel off and stick to the package.
Most office supply stores should carry and sell this paper or even a UPS store should have the paper.