Note that some older versions may not be upgradeable, so you may need to start from a clean install.
How to Upgrade
Please download the latest version of the software you wish to upgrade and follow the upgrade instructions in the docs. If you have a custom theme, refer to the appendix section of the upgrade instructions to see what changes you need to implement in your theme. If you are not using a custom theme, you can just overwrite all files as mentioned.
For support options, please refer to the software website.