Within the /system/expressionengine/third_party/ directory, copy the static_page_caching folder into your sites ./system/expressionengine/third_party/ directory.
Go to the Modules area in the ExpressionEngine control panel, find Static Page Caching in the list, and click Install.
Setup and configuring:
At the root of each of your Sites, make a directory called static_page_caching.
Set the permissions of that static_page_caching directory to writable, typically 777 on Unix servers.
If one does not exist already, at the root of each of your Sites make a file called .htaccess.
Set the permissions of that .htaccess file to writable, typically 666 on Unix servers.
A few preferences must be set in the control panel. Consult the documentation on this for more information.
Within your sites ./system/expressionengine/third_party/ directory, delete the static_page_caching folder and upload the new one from the /system/expressionengine/third_party/ directory in your download package.
Go to the Modules area in the ExpressionEngine control panel and click the Run Module Updates button.