always pick a hose, undo it, and fill from there.
there might be a writeup on bleeding the system in the link in my signature. it's pretty straight forward. park the truck downhill, lowly undo the sensor juuuust enough for air to escape while the cold engine is running. do not do this if the engine is hot because there's a risk of completely unscrewing the sensor and you don't want a hot coolant shower. :L
a variation on that is to completely remove the sensor while filling from a hose and hold that hose higher than the sensor opening so eventually coolant will come out the sensor hole.