Upload this directory to your plugins directory. It will create a 'wp-content/plugins/search/' directory.
Go to the Plugins page and activate "Search API".
You should see a notice at the top of the plugin screen telling you that you need to enable a search plugin to work with the API. Choose which plugin you want to use (Google, MySQL, or another) and click "activate".
If you have chosen a plugin that needs additional configuration, you should receive a notice at the top. Click the displayed link to configure any settings.
Requires: 2.8 or higher Compatible up to: 2.8.1 Last Updated: 2009-8-25 Downloads: 12,751