You can contact a member by sending an email, instant message, or write on their message board.
You can also initiate audio/video conversation.

To send an email or use instant, audio and video chat you need to subscribe for a Gold Membership. It only costs about the price of a Saturday night movie for two and a tub of popcorn, so it's well worth it.

Once you're an Gold Member, you can email and use audio/video/instant messaging communication tools. Here's how:

To send an email, simply go to the person's profile and click on "Email me" icon. Type in your message and click "Send".
If the person is online, you can send an instant message and start audio/video chat in real-time. The ONLINE button is green in the person's profile if they're logged in. Click it, and you're on your way.