One of the features under the user control panel is private messaging. When you click on the private message tab it comes up defaulted to the "compose message". Click on "Find a member" to show a list of registered members. Put a check mark next to whom you wish to message and then click "select marked". When it returns to the compose page, then click "Add" to put the recipient in the "To" box.
Compose your message and then click "save", "preview" or "submit".
Another feature is setting your "profile". You can show where you are located, what you do for recreation and even enter your birthdate. Then when folks log on they'll see a message when it is your birthday. :o
Fill out your occupation, interests, hobbies, etc. Now when any clicks on your user name in the members list they will see the information you want them to know about you :D