If you decide after you purchase your label, that you have to have the package picked up by FedEx you can do that over the phone or online.
You can CLICK HERE to go through the online pickup process. You will need a FedEx Account (free) to make this request.
You can call FedEx at 1-800-463-3339 and follow the voice prompts for the type of service (Ground, FedEx Express etc.)
FedEx has an excellent help page for Pickup Options. Click this link http://www.fedex.com/gb/quick_help/pup.html