怎么写英文感谢信？

Dear XXX,
Thank you so much for lending me money when i was in the most difficult times of my life. You are just like God-sent, you are simply an angel!I know how hard it was nowadays when people ask for help in monetary matter. Whenever I have enough, I will repay you as soon as I can...not only monetary gift but also my sincere thank you (from the bottom of my heart).
I will remember all the good you did to me and my family. I also want you to know how grateful I am to have a true friend like you.
Thanks again and I wish you all the best in your life ahead.

Your friend,
XXX

THANKS!

Thanks for your help, i will take money to you.

Basic Structure

1) Say thank you !

2) Make it personal.

3) Theme--worldly*

4) Thoughts on gift or event.

5) Say thank you again!

6) Closing: I love you all ect.....

Here are one example :

January 7, 1998