What is a formal letter

It's a letter usually used for correspondence between businesses or individuals, in a more formal manner than you would use for writing to a friend or family member. An excellent example of the layout and some writing tips can be found here: formal letter format

What is a formal letter ?

I would like to ask advise manager about
Friend of mine who has graduated last year and he wants to apply for PSW from Libya ,Could he apply for it
I hope you still remember that I worked with you last year as interpreter
I have not received any money yet

I would like you to do it as formal letter

Please if you donot mind