It's uber easy. I did it for my friends 01 and it took me a whole 3 minutes and that is only b/c her glove box was full of crap.

Buy them here.
http://handaccessories.com/civmaint01.html

Here is where you download the instructions after you search for your car.
http://www.micronair.com/

I did it last month for her. She got the car new so the filter was almost 4yrs old. Holy crap was that thing dirty. Definitly change it. And yes, you need two filters. Good luck and let me know if you have any questions.