Emily, can you give us a picture of the loose parts, the head tube with its fittings, and the fork crown? I've done plenty of headsets, but they've all been threaded headsets. I've been reading up on threadless headsets, however, and they differ only in the locknut/top cap. According to Sheldon Brown's site, you've probably got a 1 1/8 inch threadless headset. Direction for installing and adjusting that can be found at the Park Tool web site http://www.parktool.com/repair/readhowto.asp?id=65. Also see my recent post under the headset thread here for tips on proper adjustment. You really can do this. Get some good grease (Pedro's Syn Grease) and think about how the bearings, cups, and races fit together (make sure the bearing ring is oriented correctly). Then it is probably just a matter of greasing the bearings and bearing surfaces, putting a bearing ring over the fork steering tube against the crown race, sliding the fork steering tube into the head tube, sliding on the top bearing, attaching the top race, then the spacers, then the stem, and finally adjusting. The pictures on the Park site should make things clear.
Good luck. PM me if you have questions.