How to multimeter test a PSU?

I want to see what this fortron 530w really pushes in wattage and what not. How do I do the test, I have a multimeter, I just don't want to end up with hair like albert einstein.

put one side of the mm,normally the red on an exposed side of the wire or rail u want to test. then touch the other side to grd. to get accurate readings,make sure the rails are plugged in and working (pulling a load) when u test... these voltages are nominal and arent strong enuff to bite u (3.3v 5v 12.0v) just dont mess around inside the psu cause threre is a tiger in there and the capacitors can really knock u on your *** or worse........

You need either monster-sized load resistors ($$$ unless you make your own from nichrome wire) or tons of smaller resistors to do a good test. Whatever you use, remember that amps = volts/ohms, watts = volts x amps, and the resistors should be rated for at least 3-4 times the actual watts flowing through them or you'll burn your tongue every four seconds (the longest I can go without wanting to lick a resistor when I'm undermedicated).
And for high currents, solder joints work a lot better than crimped ones. You also don't want to draw more than about 5A through each wire, so the load resistors will have to be connected to several sets of output wires. If you know the load resistance, then you can calculate the current from the voltage, but if you're using nichrome or can't tell the ohm rating (hard to measure really low resistances, and nichrome may also change resistance with temperature), you'll need either a low-resistance current shunt or, much more convenient, a Hall effect DC/AC clamp-on ammeter, like
this one (needs to be hooked to a digital voltage meter).