Hey Alex,
This probably isn't going to be what you want to hear, but it is pretty much the standard answer around here. Read, read and then read some more. I'd recomend getting Natrual reef Aquariums, by John Tullock, and following some of the set up info in there. Keep reading this site too, it's a great source of interactive information. I think the general consensis around here is that smaller tanks are harder to maintain then larger ones, plus once you get the bug, your most likely going to want to upgrade to a bigger tank. If you can swing it, and it's not to late, you should consider something a bit bigger to start with. If you already have the 10 gal you could use it as a small sump. Just a thought. I would also recomend having your tank drilled rather than buying an external overflow. It's one of the things that I wish I had done.
I hope that at least gets you started, don't be afraid to ask questions here, and use the search funtion, it will save a lot of time. Most likely if you have a question someone else had it too and has already asked it. There is also a FAQ thread at the top of General forum that will answer a lot of your questions.
Good luck,