Your pc/browser is not set up for swing applets.
I have set it up as an awt version also.
Note: the awt version uses forest1 as its package
If you want to make a move into the modern world :) and use swing
(and above) then do the following (for IE):
There you must check the option:
Java (sun) -> use JRE 1.5.0 (something) .
If you can't find that option you must download the JDK from sun and install
As for the package/folder issue, check out the sun documentation for this.
Good luck !