Changing lighting is really difficult on your own; bring a friend the the lesson I learned. The old light was put in with toggle bolts, and there was no junction box in the ceiling. One of the toggles didn’t give up without a fight, and I ended up breaking the drywall on the window-side bolt.
To support the whole light, I had to screw the light into the drywall in the middle and other side more heavily. Since the whole lighting assembly weighs about 2 pounds with bulbs this is a mostly safe arrangement.
I’m starting to get the hang of household wiring after this past weekend. I even got a pair of new 120v smoke detectors installed. By the way, junction boxes in el cheapo contruction projects are always a challenge. In the case of the light above there was none; there was just a wire coming out of a hole. In the case of the smoke detectors, they both had them, but each was a different size, and one of them isn’t held in place by anything but plaster.