Here's a picture of my Brooder box... it's a 19 1/2" x 32" guinea pig cage I got off of craigslist a year or so ago, and I've added some cardboard around the edges to help keep the heat in and drafts out! Right now I only have cardboard around half of mine because it's in a very protected spot in my house... under a craft table, up against a wall. I may add more if it seems to be drafty, but I think it's gonna be OK!
You may use a large cardboard box, an old cooler, a child's wading pool... whatever has sides big enough that the little peepers won't hop or fly out of(they can fly pretty quickly). You may need to put 'bird' netting over the top of whatever you have, depending on how high the sides are.
A heat lamp is a must... Brand new chicks need their temp at 95 degrees the first week, then each week after that dropping by increments of 5 degrees. If your chicks act like it's too hot, then you can adjust it - don't ever stand firm to these 'rules' - watch what your chicks tell you too! They sell clip-on ones at the home improvement stores, or you could rig it up to hang over the brooder somehow. It needs to be able to be adjusted, lower and higher so the chicks don't get too hot... and I think it's recommended to get the red bulb because it makes it easier for the chicks to sleep, and they're less likely to pick at one another too. Of course you'll need chick feeders and waterers. There are a couple of designs out there, but the main thing is to make sure you place them up on something like a brick or a board so the chicks can reach them but they don't get as much bedding and dirt in the food or water.
We decided to get a digital remote thermometer... like the ones you can mount part of it outside (transmitter) and then read the indoor/outdoor temps on the receiver inside. If you decide not to get a thermometer, you'll probably be OK - the chicks will let you know if they're too cold (by huddling directly below the light), too hot (by staying as far away from the light as possible) or if there's a draft (huddling to one side of the light)... if the chicks are peeping contentedly and moving around the brooder seemingly unaware of the temperature, they're probably happy!
For the first couple of days you will not need to use anything but paper towels as bedding... the little chick's legs can't handle the slipperiness of newspaper, and if you put them in the brooder with pine shavings or other types of small bedding material, they might try to eat it and get sick or die. Put the paper towels down, load up your feeder and waterer, get the heat lamp running and warm up the brooder - all BEFORE you go to get your chicks from the PO or wherever. You want to have things ready for them when they come....
This is the point I'm at now... ready and waiting to see the cute little fluffy butts!