How to replace an headlight assy on an Ford F150 truck?

 

Owners manual has a write up with pictures on changing the headlamp bulb.

This procedure is removing the headlamp assembly from the truck, and changing the bulb with it out of the truck.

If you do not have an owners manual, you can download one from Ford :
https://www.fleet.ford.com/maintenan...ls/default.asp

Take a look on page 184 of the owners manual for the write up ( or in the Maintenance and care section, depending on the revision you have )