Please attach the code that you've tried so far. Please see these links to "how to not ask a question", "how to ask questions somewhat properly in case you are an idiot", "how to format posts" (for when you post this code), and "guide to the monastery". Thanks.
If this is homework, please read these nodes about how stupid you are for posting a homework question here:
Update: Oh, I forgot to make those links. I don't have those handy because I don't post these types of nodes over and over again. Oh well, someone else will surely reply with those links shortly. Please be patient. (:
Sarcasm. Its not just for breakfast anymore. - tye