I'm not sure what you mean by "system" when you refer to CO2. Most of us bought a regulator and built ours from there. I'd suggest you avoid the yeast based systems that aquarium companies sell. If you really want to go that route, a couple 2L bottles are just as good if not better. Your tank is small enough to use DIY, but if you want to go with a higher light level you'll be setting yourself up for less dissapointment if you just start right out with pressurized CO2. It really can't be beat.
The easiest way to get set up is to buy a regulator/solenoid/needle valve/bubble counter combo. The cheapest or most customizable way is to piece everything together yourself. There are loads of combos that will run in the $80-$300 range. After that you get a tank and you're off to the races.
Since you're running a canister, it will be easy to diffuse the CO2 into the tank. You can run the CO2 directly into the CO2 canister, or get a reactor. Some canisters will burp air if you diffuse directly into the input. A Rex Grigg style reactor is what I use, and what I would suggest. I won't go into the details on this type of reactor, as there is lots of info already on the forum. You can buy one someone else put together, or build your own. Again, buying one is easier, but building your own gives you street cred and makes you cool, and we all just want to be cool deep down.
There's a good sticky Darkblade wrote in the equipment forum. If you have any specific questions, just post them there. Forum members are generally helpful and willing to answer anything you might ask. Welcome to TPT by the way.