I have a 2002 Intrepid SE and it is time to change my air filter.
Since I am clueless about cars, I need detailed step by step instructions on how to change the air filter.
Also, how often should I be changing it?
The owner's manual will show you where the hood release lever is inside the car.
Pull this lever to open the hood latch.
Go to the front of the car and raise the hood an inch or two, locate the yellow lever
and raise to release the hood safety catch. You can now see a black, ribbed box to your left up close to the front of the engine compartment. There are two plastic tabs sticking up on the right side of it. push them in (to the left) to get them to unsnap, releasing the top of the air filter cover. Lift out the air filter, and replace with one that looks just like it. Place the cover back on the box, and snap down.
Not worth $40 for 1/2 an hour's work at flat rate, huh?
The other part of your question, how often to change, depends on where you drive. Normally should be changed every 25,000 - 50,000 miles depending on use. Check your owner's manual under the maintenance section for the "proper interval", or just change it if you have no idea when it was changed last and you have over 40,000 miles.
Air filters usually cost less than $10 - $15 at any good Auto Accessory store or you may luck out and your local Wally World etc. may have it.