This is a really big sponge filter, which I would use for angelfish or discuss. But the concept is the same. You just connect the air-line to the little tube running alongside the "snorkel", which is where the air and water will flow up and out of the filter. It's a very simple concept, rather ingenious when you think about it.
Here's mine, which is basically the same as what I recommended to you, except the triangle one is a little bit bigger. This is in a 1-gallon: