Bon je fait une personne au pif :
Dear Sir or Madam,
I am writing this to work in your store as people recommend me !
I am a 15 (change si tu veut) year schoolchild but i definitely can work at the same time! I've always wanted to work in a store because i want to see how it works and it will be an enriching experience for me of course! I'm really serious and carful of my work.
Thanks for you're time and paying attention
(Ton Prénom Et ton Nom