From the picture it looks like your electroforged Schwinn Varsity (made in Chicago) is a 1-piece crank. If the bearing cages are gone and your are just dealing with loose bearings it can be a bit of a challenge to put them back in. Do the drive side first where the front chainwheel goes. First put a nice thick layer of grease in the bottom bracket all the way around the cups, spread it around on there like you're making peanut butter sandwich and you're real hungry like. Or maybe a better analogy is put a ring of grease in there like you're putting cream cheese on a bagel. The thick grease helps hold the balls in place while you work. Now put the crank into the bottom bracket but not all the way on, leave a 1" gap to work with. Put the bearing balls in one-by-one on that side using the crank assembly to keep them in while you grab another bearing. After all the bearing balls are in on that side, rest the bike on the side you just did so that the pressure of the bike pushes down on the crank assembly and holds the bearings in. Next do the other side. The crank shouldn't let the balls fall through out of the cup, so you should have an easier time of this. Thread on your cone and adjustment assembly on the crank and get it finger tight. Everything should be held in place. Finally either put the bike on a stand if you have one, or flip it over on it's seat & bars and adjust the bearing play where the crank is free to spin. This is how I did my varsity, you should be able to get it without too much trouble.