Most car CD players don't actually have a disc tray that you insert a CD into. Car CD players are slot loading--you insert the disc directly into a slot on the face of the unit. This makes it difficult to clean the drive using traditional methods like spraying it out with compressed air. You can still clean your car CD player using a CD player cleaning kit, which is a special kind of disc designed for this purpose.
Use the applicator pad that was included with your CD player laser lens cleaning kit to wipe the cleaning solution on the small pads on the bottom of the cleaning disc. These pads will be making physical contact with the laser lens in your CD player, so it is important to apply the solution so the unit can be properly cleaned.
Insert the cleaning disc into your car CD player with the padded side facing downward. Your CD player will take the cleaning disc into the unit as if it were any other CD.
Press "Play" on your car CD player. The cleaning disc will begin to spin inside the drive and the disc will clean your CD player's laser lens.