Dear John,
I know that you had problems about school.Before i was good at every lesson i had problems too.School can be difficult sometimes but if you study and write everyday, it will become much easier.
I want to help you get better.Everyday we can go to the library and i can help you with homework. What do you say ? Do you agree ? Sometimes homework is not that easy and i think that you will need help. Hope you have a good day and remember to study because it will help you. I hope to hear from you soon.
Your classmate:(Your Name)