How do I change the air filter on my Audi A4?

I've noticed a decrease in air flow in my Audi A4 and I suspect it's due to a clogged air filter. What steps do I need to take to change the air filter?

First, locate the air filter box under the hood of your Audi A4. It should be a rectangular or cylindrical box and it may have a cover on it. Remove the cover and you should see the air filter inside. Take note of how the old filter is positioned so you can properly install the new one.