The light is more for heat than anything anything else, so it does need to be on 24/7. Start the first week at about 95 degrees and reduce by 5 degrees each week. They will move away if too hot, and huddle under the light if too cold.
I prefer a red bulb, because it seems to prevent them pecking each other. You can find lots more info under the Index in the blue bar above.
My Dad came over the other day & started laughing at the chicks under the lightbulbs. He said when he was a kid (back in the 30's-40's) the postman would deliver the everyone's chicks in one day. They were shipped by zip code & were 5 cents each. No one used lights, they simply opened the door to chicken house & dumped them in.
Well I'm not about to see if that works so I use a 75 wt for 10 chicks. They are at about 100 degrees for the first 2 days then I raise the light little by little. I then change it out to a 60 watt. By a month old they are ready for room temperature. Of course they are mad as heck when the bulb goes away but they do just fine.