MoniCA can be installed from the Open-MoniCA web page. Your computer browser should recognise the link as a Java Web Start application, download the program files from the web server and then install shortcuts on your computer.
If the shortcuts do not install properly, MoniCA can also be started using the following terminal command:
$ javaws https://www.narrabri.atnf.csiro.au/open-monica/OpenMoniCA.JNLP
Each time you start MoniCA, Web Start will check if there is an updated version available. If there is, it will be installed on your computer to ensure that you always have the latest available version.