Applet is subject to security restrictions and usually can not
access files on client. There are sevetal things you are do.
(1) You can pack the supporting files into a 'jar' file and use
the 'archive' attribute in the html code to load the files.
(2) Applet is able to make network connections to the host machine
where it come from. You can read supporting files from a URL.
I think the first method is good for loading a few image files.
The second one is useful when you have many supporting file
