Careful, you'll put your eye out kid...

But seriously, take it to somebody who understands how a threadless headset is supposed to work because you don't want to be riding along and have the steerer break or your stem to lift off the steerer, a good way to cause a nasty crash. Also, if you ride with the headset loose you'll wear out the bearings quickly or possibly ovalize the headtube on a metal frame which would suck...

Alternatively go to the Park Tool website and read the info there about threadless headset setup and stem installation until you understand it totally before you fix it yourself.

Basically the inside of the steerer tube will have either a star fangled nut or an expansion plug (star nut isn't good for carbon steerers unless there is a metal sleeve glued into the steerer). This sits immobilized in the steerer. Then your dust cap, spacers, and stem (with stem bolts loose) are pushed down by the top cap when you tighten the top cap bolt into the star fangled nut or expansion plug. This sets the headset preload. Then you tighten the stem bolts so it won't move up and down the steerer.