Quick-Pic Shops are basically photo booths dotted all around the world. There are 100 in total. When you visit one and have your picture taken the pictures are stored in your photo album.
The picture will usually contain some scenery, the city in which the Quick-Pic is in or of the racetrack for that city, but will always have your current vehicle in the foreground.
You need to find all 100 and have your picture taken in all of them to obtain Stamp 96. Quick-Pic Shops are marked on your map with little black squares and are quite distinguishable to other buildings which are in brown. Each Quick-Pic will tell you the location of the next Quick-Pic in the numeric series.