how send the leter to your friends?

what's the mean?

The sender's name and address put it one the top left corner.
The Receiver's name and address put it on the center of the envelope.
the last put a stamp on the top right corner!
then dive the letter to post office!

first find a piece of paper
second find a pen
third write sth on the paper
fourth find an envelope and put stamps on it.
fifth put the paper into the envelope
sixth seal the envelope
seventh give your friend a call to let him pick the the envelope up.

How to send the letter to your friends?怎样发送那封信给你的朋友?