To update Projectfork, you must first know which version you are currently using so you can choose the right update package afterwards. To find out which version is currently installed, login to the backend of your site and then navigate to: Extensions -> Install/Uninstall -> Components.
There you should see the currently installed version in the list. Important: If you are using Projectfork 2.0.x, you first need to upgrade to Projectfork 2.1.x before you can apply any regular patches!
Now that you know which version is installed, download the approriate update package from the downloads page. Once downloaded, upload the content of the package to your joomla root directory (the main folder where you have joomla installed) and overwrite any existing files when asked.