This is a good time to check your owners manual to see is you have one, and replace if needed. Pics to follow.
Cabin filter pics
Blower and filter out of car.
And this is which brand of vehicle?
2000 chevy Impala
Just wanted to state that a cabin filter is optional on a lot of cars. However if it was a option on your car, and your car did not come with one chances are there are provisions for one, and may only be a matter of installing one.