I NEED HLEP WRITING A SPONSOR LETTER

I want to play travel volleyball and it cost around 6,000 dollars not including food or board. i have no money at all and my parents are broke. i have been playing volleyball since 8th grade and im really good at it. If i played club volleyball since then i would be unstoppable but i had no money and i still dont but with a sponsorship i cant play.I was able to pa for tryouts which was 100 dollars and thats all i had and all my parents could help pay for.I need 700 dollars by december 4th and i need to make this sponsor letter and hopefully get enough for the month and then later worry about getting more sponsor for the rest of the money.