If you are looking to screw on a light fixture, it is important that you know how to do it properly. Many people make the mistake of assuming that it is difficult or dangerous, but with a bit of instruction, it can be a breeze.
Steps you need to follow to screw a light fixture:

The process to Screw on a light fixture
1. Shut off the power to the light fixture at the breaker box.
2. Remove the old light fixture, unplugging any wires first.
3. Install the new light fixture following the instructions that came with it; if you still can’t understand, then start with our ceiling light installation guide.
4. Plug in any wires and turn the power to the light fixture at the breaker box.
5. Test the light fixture to make sure it is working correctly.
Follow these steps, and you should have no trouble screwing on your new light fixture. If you have any questions, be sure to consult an electrician or the light fixture manufacturer for assistance.
The ceiling light won’t unscrew; how to deal with it?
If the light fixture won’t unscrew, it is likely that the screws have become frozen or rusted. In this case,
-First, use a screwdriver and gently remove the screws.
-If the screws are too tight, you can try using a wrench.
-Be careful not to damage the wiring or the light fixture itself.
-Once the screws are removed, you should be able to unscrew the light fixture by hand.
These are the easy homemade methods you can use if the ceiling light isn’t unscrewing.