I am trying to create a jar file which includes some class and java files needed, but I also would like to include some extra xml, xsl, html, txt (README) files.
I a
Add the files to a source folder and they can be included in the jar.
One common way is to have, at the root of your project, a src folder. Within that, folders for java files, and others. something like:
src/ css/ java/ html/ images/
Then you can make each of those subfolders a source folder (Right click, Use as Source Folder) and they should be available to add to the jar.