Need quick instruction how to send copy of letter as pdf to someone. I just attached it to e mail from Doc.?

Wrote a letter and needed to attach and send to someone as a pdf The Microsoft Word would not let me click on cut or paste, so I just clicked the attach box in the email and attached it that way, but that did not seem right. In layman's terms, and quick way, how do I attach a doent to an e mail.