How to pin message

I am new to blackberry...
i have had my storm since december...
what is the complete process for two people to message this way?

If you know the other person's PIN, you just go about it like you were writing an email, and you'll be given the option to make a PIN message. Simply put the person's PIN in instead of an email address, and away you go.

In BB Messenger? If so:

Open BB Msgr > press BB button > Add Contact > Type in pin of user you want to add.