Gotta Season it
Hey Hurra,
First thing you need to do with any cast-iron is season it...I've found that the best way to do this is to wash it in warm water (no soap), then coat the entire item with shortening and place in a warm (225-250) oven for about 1 hour. The shortening will bake on and make a slick coating on the cast iron item.
After using the griddle for cooking, rinse under very hot water, and use a plastic scraper to remove anything that might be stuck. Place on your stove over a lit burner to dry thoroughly. Then, once heated and dry, lightly smear the inside with a little oil or shortening and allow to cool. This will help maintain the coating that you want on the cooking surface. Also, cooking greasy foods (bacon, sausage, fried foods) the first few times also helps with the seasoning process. Never use soap or cleanser to clean the cast iron! If you happen to burn food in the pan or griddle and can't get it off, heat the pan over high heat on the burner, pour some salt into the pan and use that to scour it out. Then re-season as described above.
Hope this helps...I really LOVE cooking with cast iron pans/dutch ovens, and have used these methods with much success for many years.
Cheers,
Micki