A formal letter
Hello! I have to write a formal letter and I don't know about what or how to start.
Thank you!

Question

A formal letter
Hello! I have to write a formal letter and I don't know about what or how to start. 
Thank you!

Answer

On  which  subject  you  have  to  write.
tell  the  subject  on  which  you  have  to  write  the  formal  letter

Answer

Dear Sir/Madam,
I am writing to you regarding .......(give the reason why you are writing)

Finish your letter with
Yours sincerely,
(Your name)