From Online Manual
The Package Manager in an SMF forum allows an administrator to apply modifications to the code without needing to manually edit any of the code. It allows easy, efficient install, update and deletion of modifications and security patches. Accessed from the "Main" section of the Administration Center.
Browse Packages is the landing page of the Package Manager, initially providing an overview of new packages available, and the Simple Machines voted package of the month, both these sections are live from the Simple Machines Community site, failure to load the required information will be displayed in the event www.simplemachines.org cannot be reached.
Packages will be listed in a table in the "Browse Packages" section, any package uploaded to "/Packages" will be displayed in the table. Links will appear beside the packages depending on functions available to those packages. If a package is already installed an "[Uninstall] button will be displayed, similarly if a package can be installed but is not, an [Install] button will be shown, selecting this will guide through an install or uninstall process. A [list Files] button is available for all properly packaged packages, selecting this will display a list of all files included with the package. [Delete] is also available to remove the package and its entry on this page, where possible SMF will remove the files.
"Advanced" is displayed in a small text link at the bottom of the page, selecting this will bring up the version emulation function. This allows an administrator to fake the SMF version, allowing them to test the compatibility of a package with a certain version of SMF. Enter a number and select "Save" to change the configuration. It can be undone at any time by selecting "Revert".