Do you still have the owner's manual for the truck? Bulb replacements are usually explained in the maintenance section pretty well.
There are usually a couple different styles. The light socket unlocks from behind the light assembly with a 1/4 turn or the lens unscrews to access the bulb. If the bulb is near the headlight, you probably have to access it from behind, with the hood open. Be careful to use the correct bulb
open the hood, reach down, (might need a small hand or remove what is in the way) twist the light connector and remove the housing. Pull the bulb from the housing and replace with correct bulb. Replace housing and replace any parts you had to take loose.
reach in there behind the light kinda tight wiyh the battery more so if its a desiel find electrical connector on back of light housing grip firmly and turn to the left or drivers side of truck then pull connector from housing light will be attached and pull out of connector use bulb grease when installing new one prevents corrosion