Well, no one here answered me, but I did get the answer on doityourself.com. I want to post it here because if anyone ever comes across this light fixture again, they will hopefully find this post. Here the answer with a couple more pics that should help:

Pull the U-bar to the down position,

Tie strings, about 24 inches long to start, to the respective ends of the U-bar with, with a long end of each string hanging down..

Can you get the ears of the U-bar both inside the glass (dome) which then rests on the ears without the silver wires for now and with the string ends coming out and hanging down? (Don't let go of the dome because it could slip off of the ears and fall to the floor.)

While holding the dome, pull the strings to raise the ends of the U-bar a little at a time each in turn. The dome should rise with the U-bar. Still, be careful not to let an end of the U-bar to slip out and let the dome fall. When the dome is fully raised, cut off the strings or tape them concealed above the dome.

Better, to do for the next time or do it for this time without strings if you prefer, When inserting the U-bar into the dome, use the silver wires to hold the U-bar centered inside the dome. As the edge of the glass dome rests on top of the ears, the middle of each silver wire is supposed to pass under the ears and keep the U-bar from sliding sideways and letting the dome fall, and also cause the U-bar to go up and down as you push or pull the dome without the need for strings.