You get to them from underneath the car, first you twist the light socket out of the marker light from the back side, either a quater or a half turn, then pull the socket from the housing, there will be a clip on the back side of the housing that you will need to slide to the side, you might not be able to see it very well if there is a lot of crud built up, it will have a little lip on it you can either use screw driver or a pair of pliers on the lip to slide it to the side. Then the housing will pop out to the outside of the fender. You will need new ones, as the part you poped off was part of the housing, you will also have to paint the outter part of the housing body color, unless you don't mind the different color. Here is a couple of links to a place that has the parts so you can see what the clip and the housing looks like
