How do I pull the headlamp bulb cover off to replace bulb?

I purchased the bulp and went to follow the directions in the manual and it says to pull the rubber and cover off then ....
Well I cannot get it off...does it mean the rubber boot somehow comes off the cover or just pull hard and both come off??? I tried twist...straight off...cannot get the rubber boot off the cover...HELP!!!!

in my 90 tracker the bulb comes out in the engine bay where the wires enter the bulb houseing there is a bracket or what ever you wana call it you turn about 1/3 left applying pressure.
Im not 100% thats what your situation is but good luck