So I've done some fiddling and have been able to figure out the solution to this question. I place it here for posterity and just in case it might be useful for someone else.
Begin by downloading both the java program and installing the jre/jdk from the software center.
Having installed jre/jdk, create a symlink from your java installation path to the /usr/bin/ directory. In my case, I ran the following command in a terminal because I installed openjdk-11:
sudo ln -s /usr/lib64/openjdk-11/bin/java /usr/bin/java
Create the following Desktop Entry in a text editor of your choice, replacing 'USERNAME' with your correct username:
Exec=java -jar '/home/USERNAME/JavaFIBS2001/JavaFIBS-1.0.11_JDK16.jar'
Comment=Play backgammon online
(Of course, you will point it to the specific java program and its location on your system.)
- Save the file you created in /home/USERNAME/.local/share/applications. (Do ensure the name of the file ends in .desktop).
- Run the following command in the terminal
chmod a+x /home/USERNAME/.local/share/applications/FILENAME.desktop
You should now be able to select the program from your applications menu.
In case you are curious, JavaFIBS is client that allows you to play backgammon online against real people and robots at fibs.com and ti-ga.com (the latter site is presently down because of a server failure).