I have a 1988 oldsmobile ninety eight brouham i need to know how to change the bulb for the light thats btw the front and rear door on the outsidw of the vehicle and whats the name of it

There are lots of nicknames for those lights, on any car!! For our purpose here we will just call it a side courtesy lamp. To access the bulb try one of these: Look at the edges of the lens for small groove or slot. If it has them use a small screwdriver to gently pry it out of the fixture. OR The entire fixture may POP out of the pillar. OR Remove the interior trim piece on the backside of the pillar to gain access to the bulb. Hope this helps.