Basically, the nitrogen cycle is the process in which toxic waste products (ammonia) from your fish are converted into less harmful nitrogen compounds (nitrates). This is done by establishing a colony of beneficial bacteria in your filter. The process seems complicated at first, but establishing and maintaining a cycled tank is necessary in order to have a healthy aquarium. You cannot get around it unless you do very frequent 100% water changes in your tank, because ammonia can build up very quickly and poison your fish. And doing frequent 100% water changes in a tank over 5 gallons just isn?t realistic.
With a bit of research and patience you can easily and successfully cycle your tank. Below are some links to help you get started.
GENERAL INFO ON THE NITROGEN CYCLE AND IT'S IMPORTANCE:
BIO-SPIRA: Bio-Spira is a product you can buy that contains the live beneficial bacteria needed to cycle your tank. You might find other products sold in your local pet store that claim to do the same thing, but be advised that they do NOT work. Bio-Spira, on the other hand, does work and can significantly cut down on the time it takes to cycle your tank. It also makes the tank safe for your fish during the cycling process.
Here is a link explaining what Bio-Spira is and how it works ? there is also a store locator on the left hand side of the page. I suggest you call the store first as the info the locator brings up may be outdated: