What kind of car you do you have?
On my Contour take off the wheel, use a hammer beat the drum and it comes off.
Secondly you need two tools, hold down springs remover, and a spring remoer to remove the shoes and springs.
The first you do is position the hold down spring remover on the circle things in the middle of the shoes, like where it curves, anyways do 1/4 turn, spring pops off, you need to hold it from the back by the way, so actually that gray thing on back, that end of the clip that holds down the hold down spring, just put your finger on that gray thing, then turn the tool 1/4 turn.
Hope that made sense, I dont think it does but I dont know a better way to say it without photos.
While replacing the shoes I highly recommened you buy the hardware kit, all new springs and such.
Also Contours are oddly designed in the rear, I recommend you do one side at a time so the other side is there to guide you incase you mess up.
Hope that helps.
