It's only for the first half-day to full day or so and really only necessary with shipped birds that may have had a rough trip. I use a half-cup of sugar to a gallon of warm (NOT hot) water and the vitamin/electrolyte mix I get from the feed store. If they've had a really bad trip (as in several or more dead in the box when I open it) then I use a full cup to a gallon. Pretty much like what McMurray says. Each and every bird should have it's beak dipped in the water (just it's beak, not it's whole head) and the waterer should be right on the edge of the warm spot in the brooder so they can easily reach it without having to go into the could. I strongly favor waterers with red bases for chicks because they are naturally attracted to the color.
After the first day or so I dump the sugar water but continue to the vitamin/electrolyte mix for at least a couple of weeks.
I've never made the wet mash with the sugar water before but if ever I get a box of birds that have had a particularly rough trip I'll have to remember to try. Even if they refund your shipping losses it's heart-breaking to have a mess of chicks die on you because they had a bad trip in the mail.