The shift knob should pull straight off. If you have twisted it and it rotates then you have stripped the grooves holding it in place (ask me how I know). If you put a set of pliers or something on both sides of the shifter under the knob (put a cloth or something between them so you do not scratch the knob) and tap it up it should come off. Not too hard or you will damage the bushings down below. They can be a pain to take off and to put a new one back on. The metal shifter has grooves that run parallel with the long axis of the shifter. The hole on the knob has a plastic interior. The grooves on the interior of the knob are created when you push it down on the shifter, which holds it in place and prevents it from being easily pulled off. If that is not as clear as mud let me know.
Marcus
BTW there are no embarrassing questions. If there is some way to screw something up, someone has done it and regrets not asking before said screw up.
