For the ADJUSTMENT of the bearing, it's much easier if you have two cone wrenches ("spanners" for our UK fans) of the proper size.
The procedure is as follows: After cleaning and repacking the bearings, (Remove, clean and reinstall the balls and axle, using fresh grease.) tighten one bearing cone and it's lock nut, (lock them together, but not too tightly) on one side of the axle, then (with a wrench on THAT lock nut), tighten the other bearing cone and lock nut down (toward the first,"locked" set) until you can feel the tension in the bearing (when you spin the axle). Lock the second cone and lock nut together, (again not too tightly). The bearing should be slightly too tight, such that (when you spin the axle) the bearing feels rough. Then, using two cone wrenches, (one on each bearing cone) back the two cones away from each other, a little at a time, (stopping frequently to spin the axle) until the axle spins freely, but does not rattle when you wiggle it side to side. This way, you are tightening the cones and their lock nuts tighter together as you adjust the bearing. If you back them too far, (loose bearing,) unlock one side, tighten that cone and lock nut into the bearing (again, slightly too tight) and repeat the procedure until you get it right.
As to the use of caged balls or loose balls.......
Caged balls are easier to install, (make sure it's not upside down) But, If you use loose balls, you can (usually) add one more ball, increasing the bearing surface, hence the life of the bearing. (Campagnolo caged bearings are the only ones I've seen (there may be others) that have the maximum count.)
If you decide to use loose balls, you just use enough grease to stick the balls into the grease, (In the hub, with the wheel held horizontally.) where they will stay until you insert the axle (and locked nut), before flipping the wheel over to do the other side.
Hope this information helps, rather than confuses the issue.
Mods
lease move or treat this any way you like.