Tank of the month, we have TOTM and POTM (photo of month) contests monthly. There is a link at the bottom of my posts to the rules.
To answer your question simply and big picture- You've got bio media, mechanical media, and (maybe) chemical media in most filters. What you want is for the water to first hit a more coarse sponge, then your bio/chemical media, then (optionally) to go through a finer layer such as filter floss, and you don't want water bypassing the media. Most HOB filters use a pump in the bottom of the filter; closest to this would be your coarser filter pad, then on top of that I would put your bag of bio-media and if desired, chemical media like carbon. What you don't want is water coming into the filter and having a path to flow out without going through the medias. Some people might use a slightly different order of these medias, the result will be more or less the same, but you want the finest media last, common sense.
As far as maintenance, Bio media (ceramic rings, lava rock, etc) can be swished around in tank water (I use the bucket of dirty water from water changes) and put right back. Don't let it dry out or wash it under the tap. This should more or less never be replaced.
Chemical media usually would be changed monthly, may vary depending on the type. Coarse mechanical media like a sponge, I usually rinse the same way I do the bio media, squeeze it out in the dirty WC water. Every few months you may need to replace it, or may not. Fine media like floss, or fine sponges, usually will be too hard to get clean, and will be replaced as needed (as it gets gunked up) without affecting the tank's cycle, since the bio-media will be intact.
