Implementing a Google Custom Search into your WordPress theme is actually pretty easy but requires a little bit of theme jiggery pokery!

OK so first things first:

Create a page called ‘search’ or ‘search results’ in the admin section of your WordPress site. Take a note of the page id, this can normally be found if you hover the mouse pointer over the ‘View Page’ link or go to ‘Edit’ in the Pages menu and hover over the search page (its the number at the end you need). I would also select the full page template for the search page …