Your cover has four mounting fittings (one under each corner) that snap in place. To remove the cover, lift the front carefully and gently increase pressure until the front two release, then ditto for the two under the back corners of the cover. When you get it off, a look underneath will show you exactly how they work.
The air filter is under that big black box on the left (as you face the engine) and you will see six (I think) clamps that secure the top. The air enters the lower half of the box (see the inlet coming back from the grille area), passes through the filter, and exits the box on top, rear, en route to its destiny in the combustion process. When you change the filter it's a good time to remove from the bottom of the box the dirt, feathers, and other detritus. If the filter looks really clean, you could just rap it on a hard surface to get the bits out, but they're cheap so why not just drop a new one in. You might want to research K&N filters. They're costly but last a long time (they're cleanable) and according to K&N will bump your hp a little bit because they flow air faster. There are two sides on this issue, one favoring the benefits of a K&N and the other supporting the fact that a building full of German engineers might know something about what constitutes proper air flow. The K&N tends to be noisier than an OEM (and not necessarily a bad sound) and some people equate a louder sound with better performance as measured by their butt-o-dyno.