Hey corester123,
Yep they are right. AC circuits are a little more forgiving (SOMETIMES) but why not hook them right from the get go? Just a few tips.
Black is the HOT lead. On a socket, this will be the lead that goes to the center post on the bulb. (Smack dab in the middle, the eyeball or nipple to say - {I like nipples})
White is the NEUTRAL lead. This is the lead that goes to the assembly that is threaded on the socket (In other words, where the bulb screws into, the inner outside of the socket or the female part of the socket).
Heck, this is getting sexual! My apologies to the lady's in the forum.
Green is the GROUND (if it has one). The ground is hooked to any metal portion of the assembly that holds the socket (For example, if it was a metal lamp you had sitting on a table, it would be hooked to any part of the lamp housing). The purpose of the ground is if there is a short circuit in your wiring and you touch it, the electricity is grounded (since somewhere in your house, there is a metal tube that goes into the GROUND) and travels to the entire planet earth, which is MUCH larger than you, so you get less of a shock - (resistance and all that technical junk).
On a plug, if it is a polarized plug (the ones with two prongs, one fat at the end and the other slimmer), It's self grounded. I don't like these (CACA)!!!!!! Yes they are safe BUT all my stuff is three prongs, Hot, Neutral and Ground. Spend a few bucks more to not burn your stuff up! (Like your house, your kids and maybe your old lady, Hmmmmm,,, strike the last one, glad my old lady don't get high!)! ---- (Just kidding)
If you insist on using the self grounded stuff the wires that have ridges in them or a stripe on them are USUALLY the polarized side (self grounded) EXCEPT SOMETIMES there are no ridges (smooth) and then USUALLY, the wire with the printing on it MAY be the polarized ground (Always check EVERYTHING, I TRUST NO ONE).
If you insist on using the self grounded stuff, take like a 9 volt battery, hook one side with a piece of scrap wire to the polarized plug (the fat end) and wrap the other end (stripped as in naked of insulation of course) around the base of a cheap 12 volt Christmas or 12 volt auto light bulb. Then touch the tip of the bulb (nipple), to the remaining battery terminal to determine what your leads are.
Once you determine which lead the power is going through (remember, you hooked the battery to the fat plug), Make sure this lead is hooked to the WHITE wire on your socket. (The GROUNDED plug).
OR, just bypass all this shit, protect your shit, and use a three prong dedicated ground for all your shit (That's what I do)!
(SHIT, hope I can say shit!)