The dialog box you see is your incoming messages. 

To clear your incoming messages when you're done reading them, merely click on "Clear" (You will want to make sure you "Refresh" first to make sure no missed messages are deleted). 

Up top is also a "go invisible" switch.  By clicking that, you will cloak yourself from other TRHMessenger users during your session.

The Window refreshes itself  once every 20 seconds.  This is how the system checks for additional messages.  The timer is displayed on the page right under the "Send a Message" command.

At the bottom, you can list all users, list all users currently online, and view your friends list.

To send a message, click on "Send a Message". 

The middle window is a record of your Outgoing messages.  You can choose to clear these as well.

At the bottom is your "Send" window.  The drop down menu allows you to select a user to send a message to.  If you click on [textfield], it will switch it to a dialog box where you can choose to just type the name.  It's reccomended that you use the drop down menu.

If you have any "friends" saved, the drop down menu will list them first.  Enter your message in the text area beneath that.

If you wish to cancel your post, click on "Cancel Post", just above the display.

These screen shots have been taken using Netscape v4.79.  TRHMessenger may appear slightly different in later versions of Netscape, or versions of Internet Explorer.