If you want help with a Java error, please post the full text of the error message and stack trace if present.

You're trying to add the applet as an ItemListener and an ActionListener, but although it has actioPerformed and itemStateChanged methods, it doesn't implement those interfaces.

Incidentally, I strongly recommend that you follow the Java Coding Conventions - particularly the naming conventions - class names start with an uppercase letter, method and variable names start with a lowercase letter. Java names follow 'camelHump' format where the first letter in each following word in the name is capitalised, e.g. Applet3, myContentName, totalPrice, etc.

These aren't rules - the compiler won't complain if you don't follow them, but they are pretty much universal among Java developers. If you want people to help with your code, or if you're thinking of working in a team at some point, it's advisable to follow the conventions.

Act in haste and repent at leisure; code too soon and debug forever...
R. Kennington