How do I use a built in wet/dry filter??

I recently bought a 20gl acrylic tank at a swap meet for $15.00. It has 3 built in compartment on the back, came with I believe to be a trickle plate. The 1st compartment (furthest right) has a hole at the top for a some kind of tubing?? The center compartment is where the trickle plate sits. The 3rd (left side) has slots at the very top (for overflow??)

So what exactly do I need to use this?? I know bio balls go below the trickle plate, but I'm pretty ignorant on what equipment I actually need to make this thing work.

Ant advice or links are greatly appreciated.

There are a few ways to go about familiarizing yourself with the media, placement and operation. If you have a local aquarium society, take the tank there and you should get all the advice, help (and maybe parts) that you need. If you have a knowledgeable expert in an LFS, then make an appointment and take the tank there. I can point you to web sites or describe the operation, but since it may be missing parts (return tube, media, media holder, pump), I think you might have better luck with a hands-on discussion with someone.

ps: 15$ for a 20g with a wet/dry.... sweet :o)