Hello Mr./Mrs. (name of contact person),
 
My name is (your name) and I am a student at East Palo Alto Academy High School.  I am contacting you because I would like to find out more about the possibility of volunteering at your organization, (name of organization).  Would please share with me how I could volunteer and what dates and times you need someone to help.  Please let me know the details.
 
After hearing your response with the needs at your organization, I will respond with my decision.  Thank you for your time and have a wonderful day!
 
(Student's Name),