How do I send Private messages to a member ?

Login and Click on "messages" towards the bottom of your members menu.  Click the tab "Write new message", In the "To" box, start typeing the user name and the system will show a list of users with that name, and choose one or just type the user name. Then fill in the form.

When that member loggs in, they will see a notice at the top of the page telling them they have a message waiting.
If the member is logged in when you send the message, they will see the number of messages on their members menu..   Messages(1).. or Messages(2).. depending on how many there are waiting.