Here are several utilities supporting Jo's D&D campaign. This product depends on the Java Web Start technology from Sun. You must have installed it first before this product will run. If you can see links below then you have already installed Java Web Start and can go ahead and launch Hex Files. If it instead says "You must install Java Web Start", then pick a link from the list following to install Java Web Start.
Alternatively you can try to run the utilties direcly from your browser. Those applets are located on this page. You need to have installed the Java Plug In for Sun's Java 1.4 for those to work though.
Here is where you can download and install Java Web Start for several operating systems. Pick J2SE 1.4.1 JRE (not Sun ONE Studio!) or Java Web Start 1.2 where you have the choice.
Note: you will get a security warning saying that the software is requesting unrestricted access to your filesystem. This is so that it can save downloaded file to your disk. If you want to run the program, click "Start". If you consider this too risky, click "Exit".
You can review the help documentation for the product here.
The internal page for these applications is here.