I've recently completeted 100 hours of volunteer work?

Question

My Highschool requires this to be documented and to be stamped by the company/place you worked at, what should the letter (document) include my name, date, etc anything would help

Answer 1

On organization letter head with the date signed by the director or head of volunteer services or program director who supervised your work

This is to certify that between __ and __ Your Name completes __ hours of volunteer service for our organization.    We appreciate his efforts very much.  

Optional additions might thank the school for encouraging volunteering or cite any special things you did. That is nioce but not necessary.

The organization where you volunteered probably knows how to write the letter bec they probably do it a lot.