STOP! If you only ordered the atomizer you don't have a working setup. The cartridge that comes on that type of atomizer is empty - it's only meant as packing material. If you fill that with liquid, put it on the atomizer, and set it up right it will send liquid draining out all over the place.
If you want to use it for it's intended purpose you need to purchase the polyfilled cartridges designed to go with it. They are normally sold in a 5 pack. I'm not providing a link because I don't know if you purchased a Type A or Type B atomizer. You need to be certain you order the correct empty cartridges for the type of atomizer you bought. The cone type and cylinder type atty use different cartridges and they are not interchangeable.
That, or you can just use it as a dripping atty without the polyfill cartridge. The empty cartridge that came installed on it can be used in lieu of a drip tip.