To do that, go to the "User Control Panel."
From this page, move your cursor over (or click on) "Overview" and select "Board Preferences" in the drop down.
You will see this screen:

You can determine how and if you want others to contact you, as well as set your time zone. If you are in the U.S., don't forget to use the "DST" time when appropriate.
Remember to click the "Submit" button to save your preferences.