It is used for locating were users are online and paging them. To find a user enter their name then click the 'Find' button. This will say whether they are logged on and where they are. if you find the user you are looking for you can send them a private message by typing it in the input line and clicking the 'Page' button or hitting Enter. Your message will be displayed in the small chat window as well as any replies. Private messages also show up in the Main chat window, which is still in the background.
Private messages show up in white.
The last important button is the 'Page Clan' button. The 'Cancel' button will take you back to the Main Chat window. The button with the 'Pound' sign on it is the options menu button. Clicking this will open a window of options. The options menu also contains a separate menu for sound volumes.