Within the /system/expressionengine/third_party/ directory, copy the primary_category folder into your sites ./system/expressionengine/third_party/ directory.
Within the /themes/third_party/ directory, copy the primary_category folder into your sites ./themes/third_party/ directory.
Go to the Extensions area in the ExpressionEngine control panel, find Primary Category in the list, and click Enable.
Setup and configuring:
Use of this extension requires that a few preferences be set in the extension settings. Consult the documentation on this for more information.
Within your sites ./system/expressionengine/third_party/ directory, delete the primary_category folder and upload the new one from the /system/expressionengine/third_party/ directory in your download package.
Within your sites ./themes/third_party/ directory, delete the primary_category folder and upload the new one from the /themes/third_party/ directory in your download package.
The extension will update automatically, and requires no further action from you.