You can talk by typing in the box at the bottom of the window. When people talk, the text appears as word balloons. To move to a different part of the room, click where you want to go. Depending on the amount of lag, there will be some delay before your face actually moves there, since sparky waits for confirmation from the server. To send a private message, target the person you want to send it to by clicking on them first.
Private messages appear in italics.
If you want to stop sending private messages, click on yourself, or the black border which surrounds the room. Many faces will appear with closed eyes, indicating that the other users aren't using sparky. These people will be able to see your movements and the changes you make to your face. The numeric keypad is used to change your appearence. You may have up to 3 props.