you unscrew the light bulb and put another one in from auto zone. There sholud also be a manual that came with the car (alternatively see if you can find it online) which should help you with the work.
Pull the carpeting behind the brake light. Unclip the assembly, replace bulb.
To change a side light bulb on an Audi TT, remove the light lens by unscrewing the screws holding it on. Then, remove the old bulb and insert a new one. Replace the cover and tighten the screws.
To replace the tail light bulb on a 2008 Audi A6, start by opening the trunk and removing the access panel or cover located behind the tail light assembly. Once exposed, twist and remove the bulb holder from the assembly, then pull out the old bulb and replace it with a new one, ensuring it clicks into place. Reinsert the bulb holder back into the assembly, replace the access panel, and test the new bulb to confirm it’s functioning.
It is not a serviceable part.
To replace the brake light bulb on an Audi A3, first, open the trunk and locate the tail light assembly. Remove the appropriate access panel or cover, then twist the bulb socket counterclockwise to release it. Pull out the old bulb and insert the new one, ensuring it's securely in place, then reassemble the socket and cover. Finally, test the brake light to ensure it's functioning properly.
I've written it up here... http://samboutros.wordpress.com/2007/04/02/2003-audi-a4-bulb-replacement/ Steps, pictures and links to bulbs...
howto change 2007 kia spectra parking light
The brake light bulb on a 2007 Cadillac CTS can be replaced by opening the truck, removing the rear cover, and disconnecting the wiring harness. The bulb can then be twisted, removed, and a new bulb put in its place.
To replace the front light bulb on a 2001 Audi A3, first, ensure the vehicle is turned off and the keys are removed. Open the hood and locate the back of the headlight assembly; you may need to remove the plastic cover or clip. Disconnect the electrical connector from the bulb, twist the bulb socket counterclockwise to remove it, and replace the old bulb with a new one, ensuring not to touch the glass part. Reconnect the electrical connector, secure the assembly, and close the hood.
Open bonnet, remove anything in your way to the rear of the headlight (air ducts, battery, etc.), remove rear panel from the light, replace bulb, use small hands.
To replace the rear bulbs on an Audi A3, first, open the trunk and locate the access panel on the rear light assembly. Remove the panel by unscrewing or unclipping it, then disconnect the wiring harness from the light assembly. Twist the bulb holder counterclockwise to remove it, replace the old bulb with a new one, and reassemble the light assembly by reversing the steps. Always ensure the new bulb is securely fitted and test it before closing everything up.
To change the boot light bulb on an Audi A3, first, locate the light fixture in the boot area. Carefully pry off the light cover using a flat tool or your fingers. Replace the old bulb with a new one, ensuring it is securely fitted, and then snap the cover back into place. Finally, test the light to confirm it’s working properly.