Hope this helps you get started a little bit more:
I agree with ringham, definately look into the Eheim Professional II & III series canister filters and return the Marineland Tidepool II that you bought. The Marineland is a wet/dry filter, which is more geared towards saltwater. Although there are a small handful of people have successfully used a wet/dry filter in a planted tank, I think you'll find the general consensus is that canister filters are the way to go with planted tanks. I can't emphasize how important it is to research equipment before you buy it, otherwise you may end up (as you already have with the filter) buying things that you don't need and returning them and/or replacing them down the road only after you discover that they aren't what you need.
Normally I'd recommend compact flourescent lighting, but for a tank of this size I feel that metal halide is really the way to go. It might be more expensive than using flourescents, but on a tank of this size a few metal halide pendants will give good light spread, and at the same time move out of the way easier during maintenance.
Also, for a tank of that size you will definately need some pressurized C02, don't even bother looking at the DIY C02 recipes. You will need a bottle of C02, a regulator, needle valve, checkvalve, selenoid, bubble counter, and a reactor or diffuser. Although you can peice your own C02 system together cheaper by individually purchasing all of the previously mentioned parts I think you'll save a lot of aggravation and time by going with an all-in-one regulator
such as the Milwaulkee MA957, JBJ or Topgun. Also, to get the C02 dissolved into the water you're going to need a reactor as well, which can plumb right into the outflow of whatever filtration method you end up with. You can buy a comerical C02 reactor for anywhere between $60-$80 or you can build your own
for around $15-20 which works every bit as good, maybe even better.
I would recommend you return your gravel, or at least mix it 50/50 with flourite. Plain old gravel by itself doesn't provide a whole lot in the way of nutrients for the plants. Most people either use flourite, a mix of flourite and gravel, or eco-complete. Eco-complete is also a very very good choice, but is kinda pricy. If you can afford it though, it's black coloration is very nice looking. Plus you don't hafta wash it, which is good if you're a lazy bum like me.
Just some things to think about, there's a lot more to it though...
When you have a moment, go to the picture section of this forum and look at some of the larger tank setups that people have, hopefully that should help get the gears turning.