Generally, you release the latches that hold the cover in place, lift the
cover, and replace the filter.  You may have to loosen the clamp holding the
intake hose.

When you finally find out how to replace it, think about replacing it
with an air filter that will go 100,000 miles or 4 years before it
needs replacing again.

http://www.amsoil.com/storefront/eaa.aspx?zo=1690163
Absolute Efficiency
AMSOIL Ea Air Filters are the most efficient filters available to the
car/light truck market. Ea Air Filters' synthetic nanofiber media
removes 5 times more dust than traditional cellulose filter media
alone and 50 times more dust than wet gauze filter media. AMSOIL Ea
Air Filters have a service life of 100,000 miles or four years,
whichever comes first.

Better Air Flow
AMSOIL Ea Air Filters allow more airflow than filters that use
cellulose media alone. Cellulose fibers are larger than nanofibers,
and have larger spaces between the fibers, causing contaminants to
load in the depth of the media and plug the airflow path, which
results in higher restriction and less capacity. The synthetic
nanofibers in EaA Filter media have submicron diameters and small
interfiber spaces, which result in more contaminants being captured on
the surface of the media and lower restriction.