Agreed, I was thinking about upgrading a HOB Penguin 250 with a Cascade 1000 on my upgraded 35g hex(was on a 29g previously)! Your 700 is only rated for like a 75G max as stated by the manufacturer. The '700' stands for 700LPH or roughly 185GPH, but most on here recommend at least a 5X turn over rate for canisters, or ~500GPH or better.
You can continue to use it, but plan on at least a Cascade 1500 to add to your tank. I have a 1500 plus a sump w/~900gph return pump on a heavy stocked 90G and a 1200 with a sponge filter and magnum 250 on my lightly stocked 90g. I do keep up with my oscars in the heavy stock, but bigger water changes per week help with this.
Check the media sticky at the top of this forum, it'll lead you in the right direction...But here are the basics.
1st stage is the coarse sponge, mech. filtering the big stuff, but also a good place for beneficial bacteria to take hold(be sure to only clean this when needed with dirty tank water, to preserve your bio filter here). The carbon is for chemical filtration, but unless your getting rid of medicines or fish stank odor, this really is not needed-per many on this site alone. The white 'foam' material is actually just polyfill pillow stuffing cut to fit your trays. It 'polishes' the water to get the micro particals out. This is the first to get clogged so it stays in the top tray.
Some set up tips from my experience.
Sponge on the bottom, but this tray is wrapped with a 1x16" strip of filter mat, to prevent bypass of the media. Next tray is your bio media, I added ceramic rings to all of mine, these are readily available at your local fish store. But you really do need more bio media for any Cascade filter as they lack this out of the box. Then top it off with a single 'Bio-floss' poly pad. Change the pad (in your case) once a week, the rest, *rinse* like once a month.
Don't use carbon unless there is a need, is used, place it on top of the sponge.