2003 Pontiac Montana Air filter

How do I change the air filter into the cabin of the vehicle. At our last oil change, the mechanic brought out the air filter for our van and showed it to my wife. She said it looked bad but the mechanic blew it out with an air hose and put it back. I'd like to change it but there are no instructions on how to do it. Wondering if my wife told me the right thing - thinking she might have meant the air filter for the engine?