Ok the filter media will help but you still have to make sure the tank is cycled before add any livestock(fish, crabs, etc.) The tank should have no forms of live besides bacteria until a couple weeks after the cycle has finished. You have a test kit to check ammonia, nitrite, nitrate and ph right?
The best way to start a cycle is to dose pure ammonia until you reach 4 ppm
in your tank.
The bacteria on your rock and in your filter will start multiplying and will turn the ammonia into nitrite after a week or two the. Nitrites will be turned into nitrates. Once you have 0 ammonia, 0 nitrite and lots of nitrates you can do a 10-20 % water change every day or two until you get your nitrates down to 10 ppm
or lower. Your cycle is then complete.