Warning : Do not attempt to upgrade Jomres if you have a license/support key which has since expired.
During updates to Jomres it is common to need to update plugins too. If you downloaded and installed some plugins while your license was valid there's a good chance that your old plugins will not work with the newer version of Jomres. If you want to upgrade after your license has expired you'll need to purchase a renewal license key and enter that into your Site Configuration -> Misc tab before attempting to upgrade your installed plugins.
This feature makes upgrades to Jomres extremely simple by allowing your server to communicate directly with the jomres.net updates server, download the newest version and deploy with minimal effort, however it's important to remember after upgrading you should ALWAYS run install_jomres.php after upgrading
Just click on the upgrades icon and follow the onscreen instructions. As those instructions are pulled directly from the updates server it's not appropriate to repeat them here as they're liable to change, but they are very straight forward.