As Joe noted, use a thin rubber glove or anti-skid material, whatever supplies traction, and press firmly up while turning the ring to disengage from its base. You may have to use both sets of fingers for that maneuver, but try not to shatter the lens in the process. The vinyl ceiling material often presses down so much that disengagement of the ring can’t be done bare-handed.
As I recall from prior threads here, the prongs on LED bulbs may need to insert in the socket a certain way, and may require clipping shorter.
Also if you expect to save and reuse the halogens, as with automotive lamps don’t handle them bare-fingered; skin oil can ruin them.
Joel