One of the great things you can do here is send a private message (known as a PM) to any member. Think of it as an email system within the forum. As the name says, these messages are private, unlike normal posts which anyone can see.
How do you do it? Easy.
Just click on the "pm" button on the bottom of a post by the person you want to send the message to. You can also do this from the Memberlist which you get to from the link on the main menu. This will take you to a screen where you write your message, you also must put something in the subject line. When you are ready to send, just click on the Submit button as you would when posting in the forum. It looks something like this;
To get to your private mailbox just click on the link on the main menu. This is the link that usually reads "You have no new messages", it will change and let you know when you have new PMs in your inbox.
The forum can also notify you of new PMs in your email if you wish. This is one of the many settings in your Profile, to set these just click the radio buttons and don't forget to save your new settings.