Letter How To Convince Friend Parents To Participate In

I would like to write a letter to my friends parents so they let them to be part of my court, but don`t know excatlly what to said. They don`t have a clue what is a quinceanera and one important things is that they will have to agree to pay for their dress. How I do this?
My parents is asking me to do this but don`t know how can you help me. Please
Posted by Angelina Tromble; updated 03/07/09