Answer:
Dear (Fill in Name),
I understand that you are in need of a babysitter. My name is (Fill in Name), and I would like to apply for this position. I am (Fill in Age), and very responsible. I love to help whenever I can. I have (Fill in Average Grades) and participate in (Fill in extracarricular activities). I am looking forward to working for you and your child.
Sincerely,
(Fill in Name)