|MadSci Network: Zoology|
According to the recipe I found at Dr. Scott Shalaway's website http://web.mountain.net/~shalaway/hummingbird.html (I've seen these recipes around in a number of books and magazines), you should mix one part sugar to four parts boiling water (boiling helps the sugar mix easier with the water and makes it last longer in the feeder). So if you were making 4 cups of nectar you would mix 1 cup of sugar to 4 cups of water.
Make sure that you use a measuring cup for solids for the sugar and a measuring cup for liquids for the water. After the sugar dissolves let the nectar cool down to room temperature (you could even put it in the refridgerator if you wanted to). After the nectar is cool then you can fill your feeder, hang it in a place where you can watch it comfortably, and wait for the hummers to arrive. Depending where you are, the ruby-throated hummingbirds should be migrating back north fairly soon.
Try the links in the MadSci Library for more information on Zoology.