Check to make sure that there is not a hydralic cycinder on the engine side of the firewall or a plate under the floor where it may be. If so you have a slave cyclinder that works the clutch. Make sure that it has plenty of fluid in it. It is self adjusting.
And the manual type if you get under the truck and have someone push the cluth you sould see a linkage moving neer the front of the transmisson on the drivers side. There will be an adjusting rod on that linkage make the linkage longer and the cluth peddal disengages the cluth sooner and shorter helps it from slipping. If that don't work you may have to put a new cluth in the truck
The clutch has an internal adjusting ring. You bump the motor until you see the bolt in tab that secures it. Remove the bolt in tab and with a drift and hammer move the adjusting ring until there is approximately 1/2" between the bearing and the clutch brakes. You adjust on the ring with someone holding the pedal down but you measure the gap with the pedal released. Only after this is done can you do anything to the linkage as mentioned in the other answers. Usually you never adjust the linkage on these trucks.