This version of the applet requires Java 1.3.1. If you do not see three buttons in the above box then either you have an older version of Java on your computer or else Java is not enabled in your browser at all. If you are using an old Java version, you can try the older version 5.0.2 of the applet, which is compatible with Java 1.1.8.
Mars24 cannot accurately determine the time on Mars unless your computer's time and timezone are set correctly.
A "User's Guide" to this applet and "Notes about Mars Time" are accessible via the applet's Window menu.