Thank You Letter Coach I Want To Write A Letter To My Swim Coach!?

I want to write a letter to my swim coach!? - thank you letter coach

I am in grade 10 and I'm in the school swim team coach and I want to write a letter of thanks to my swimming, but I'm not good with letters and letter ..
I am writing this letter because it is a great coach and could not be here next year could result from D: So yes, please help me:]

Thank you!