Pull the door panel off, it's in there.
The Haynes manual explains this process fairly well-just a few screws (don't forget the two or three along the bottom of the panel!) I rate this task as "easy", I just found the bulbs to be exorbitantly expensive for what they are ($5or6 CAD for green ones from Ford!-Canadian tire had white bulbs to fit for only a buck!!!)
If you don't have a manual (worth getting anyway) you may be able to borrow one from your local library.
Good luck.