Park with your wheels turned all the way to the left. Look in the wheel well towards the passenger side you'll see 2 screws holding the bottom of the mudgaurd up. Take them out.
Next get under the bumper. You'll see 2 or 3 screws (can't remember I only have one now
) take out those screws.
Pull down the mudgaurd next the wheel well liner piece (pull them off of the tow-hook)
Pull the liner piece back and you will have access to the filter.
I recommend wearing gloves, the plastic can cut up your hands.
I'd also check the Install for this on this site.