Power supplies confuse me

These new fangled PSUs have got the wrong amount of plugs on the back. They’ve just got one. Where are you supposed to put the monitor?

My monitor has one cable that’s supposed to go into the back of the computer, and my computer’s got one cable that goes into the back of the computer and a wall socket. The PSU has two three pinned connectors at the back, one in, and one out. There’s no where else to put the monitor, and I haven’t got a converter of sorts for the monitor cable.

So just recently I’ve been looking for a new PSU so I can get a better graphics card, and I’ve noticed they all have only a single port on the back, presumably for the computer, not the monitor.

Where do you poeple plug your monitors? I’ve seen pictures of these strange single ported computers actually working. How?!

I’ve tried Googling for some help but it just turns up lots of internet shops selling cables for the insides of the computer rather than the outside.