Sabrina121:There should be a number that you can call for information....I suggest calling the number ask them that question AND ask them if they have any tips!
I think I'd probably not call and ask them how long it should be. It could come across like you're trying to do the bare minimum.
I just suggest sitting down and writing and see how long it takes to get your point across. I think you'll find that 500 words is pretty easy and you may end up writing more.