Make sure your brooder is draft free...very important. A heat lamp is a must...place it in a corner above the brooder so if the chicks get too warm they can move away from the heat....placing it low or high above the brooder, is something you will have to figure out by watching the chicks. If they are all clumped together under it, indicating they are cold, you may need to lower it closer to them. If they are never under it, you need to raise it as it's too hot. Cover the rest of the open area on the top with towels, tarp, whatever to keep drafts out and keep the heat inside.
Make sure they have food and water available 24/7 for as many weeks as they are in the brooder. The day of arrival, the next morning at the latest, pick up each chick and stick there beaks in the water...repeat a few times a day until they get the idea of water and where it is. Just make sure they are drinking water so you don't get pasty butts.
My brooder is on an enclosed porch with a room heater on 24/7 so the room temp is around 80 degrees. First week temp inside brooder should be at least 90 degrees. The next week you can lower it no more than 10 degrees. Each week you lower the temp 10 degrees. Do not put them outside in a coop until they are fully feathered, as they will freeze.
The dimensions of my brooder is 2' x 2' x 4' long on legs, wood walls, top on hinges for opening with hardware cloth stapled to it. I drape one or more towels on 1/2 to 3/4 of the top area to keep the heat inside the brooder...then hang the heat lamp in another corner. Placement of how high or low you place the heat lamp is regulated by how the chicks react to the heat. More heat needed, I lower the heat lamp. Less heat needed, I raise the heat lamp.
Good luck with your new babies!!!!! They are so much fun and interesting to watch. I ordered four ducklings and four chicks to arrive in March, so like you, I am soooooo excited to see my new babies. I already have three Welsh Harlequin ducks 4 mos. old and four chicks 4 mos. old. so I will have a full house including the newbies.