They are tight, but the silver metal ring holding the glass lens is held into the rest of the light assembly by tension and can be popped out by gently prying up the outter edge of the ring which is next to the glass lens
with a flat screw driver...the rest of the light assembly will remain in the hole in the interior skin.
The glass lens is separate from the ring holding it in, so be careful not to drop the glass as you take it out ... The halogen bulb to be relaced should say 12V
and have a wattage number on it...probably 10 or 20 watts.
You should be able to get replacement bulbs at a hardware store...or you can get them from a dealer, but they are likely to cost more there.
Be careful not to touch the new halogen bulb with your bare fingers as the oil from your skin will shorten its life...just pull out the old bulb and put the new one in...then place the lens in the silver ring and pop it back into position...there are a couple of notches to line up as you put the ring & lens back into the light assembly and there are 2 tension tabs in opposite positions on the ring...it's pretty straight forward.
Hope this helps...