I see in you aquarium info that you answer No to knowing about the nitrogen cycle. So it would probably be good to read this:
http://www.fishlore.com/NitrogenCycle.htm.
The easiest thing for you to do right now is get some Tetra SafeStart (if you can find it) and add it to your tank. It has the benificial bacteria you need, and will cycle your tank right away.
The harder option would be to do 50% daily water changes using Prime as Lucy suggested. You will need to do these water changes until you have zero ammonia, zero nitrites and some nitrates. (This could take several weeks) At that point your tank will be fully cycled and you can just do routine partial water changes on a schedule that suits your tank.
The third option is to place some filter media (or gravel in a nylon stocking) from an established heathy tank into your tank. The bacteria in the media or gravel will really jump start your cycle and it may only take a week or so.