http://huntsville.about.com/cs/food/ht/Cast_Iron.htm
Wash skillet in hot, soapy water. Rinse thoroughly and dry completely.
Apply a thin coating of melted shortening (Crisco, for example) or vegetable oil with a solf cloth or paper towel.
Preheat oven to 350 degrees. Place skillet UPSIDE DOWN on top oven rack.
Place foil on a cookie sheet and place on bottom rack of oven. This will catch the drippings from the skillet.
Bake in oven for one hour.
Turn oven off. DO NOT OPEN. Allow skillet to cool down in oven (several hours). There may be a film on your cookware, this comes off after use. You will have to use it a couple times as a test.