You could say " I'm (your name), i'm (your age) and i'm candidate to the (choose the job you want the most). What I love in this job is (you list some of attract of this job). I'm think i'm the most skilled because (you say some of your qualities). I'm very intressed in this opportunity to learn and gain experience because it could help me in the future. Sincerly, (your name again + "here is my number if you would call me back" you can give your real telephone or a fake one, nobody will know). "
En espérant t'avoir aidé.