1. Private Message from contact menu
While viewing a message from the person you want to send a private message to, click on the 'Contact' menu button, and click on the 'Send [user] a private message' menu item.
2. Private message from profile page
While viewing the profile of the person you want to send a private message to, click on the 'Send [user] a private message' link.
Private Message Form
Both the previously mentioned steps will take you to the private message form, where the person you are sending the message to is displayed under the text 'To :' along with a subject and message text area. When you are ready to send your private message, click on the 'Post' button at the bottom of the form.
Private Message Listing
Once you have posted your private message, the message recipient will see it displayed in their private message listing when they view their private messages page. To view your private message listing, click on the 'Inbox' link, located at the top right-hand corner of any page.