Finally an overhead light in my room

It had been bugging me ever since we moved in that there were exposed
wires in the ceiling in 2 rooms upstairs. I somehow had found a light
fixture from somewhere here and 3 wirenuts to attach it. But the problem
was not knowing which wires did what.

The wiring was incredibly crazy but I guess that's how this place was
done when it was originally built. As the wiring went, it allowed for a
ceiling fan to be installed and have the fan and light independently
switchable. I don't need a ceiling fan - in fact, the ceiling here is
way too low to allow me to move around with one without accidentally
damaging it. I think these 2 upstairs rooms had one in each of them. The
former tenants must have been ceiling fan crazy, as the kitchen and one
other room downstairs has them. They're in the other apartments as well.

There should have been only 2 wires to connect a fixture to. There were
3 bunches. !! I had a plan and used a circuit tester to find the live
pair. This thing is basically a little light with 2 metal probes at the
end. It lights up when I find powered wires. What about the other two
bunches?

The electrical socket behind my bed doesn't work. So I'm guessing one
set is supposed to connect to the live pair. And in order to have a
switchable circuit, you have a direct connection to one wire, while you
have the other interrupted by a switch. Using my voltmeter's continuity
tester, I found which pair goes to the switch. Presto.

A little fight with the wirenuts (I needed 3) and I now have an overhead
light I can switch on and see better. I see there's 2 sets in the other
room, so figuring that out and putting in a light there should be
easier.

At some point I might connect the electrical outlet behind my bed. Or at
least put in a grounded 3 prong outlet.