Hi Debbie, this is Kaspars (author of this blog). I am sure that Martin (author of the plugin) will read your question and respond here.

My suggestion for you would be the following: create a Google search box through your AdSense account (setting the colors and other configuration) and paste the resulting HTML code in your theme’s file header.php (under Presentation > Theme Editor) in a location you want.

After having a quick look on your site’s code, it should come right after your logo and slogan — replacing <?php include (TEMPLATEPATH . '/searchform.php'); ?>.

The other option would be to use Direct Code Ad from Product drop-down menu when creating a new ad “unit” through AdSense Manager plugin, and paste the search box code you generated through your AdSense Account. But notice that you will still need to edit the header file of your theme, in order to place code generated by AdSense Manager (like <?php adsensem_ad('name'); ?>) instead of current search bar.

Regarding the AdSense for Mobile — for that you must edit your theme’s code to include the PHP code generated by Google when you set up a new mobile ad slot (more in Google Help for Mobile).

If you have any more questions, please ask.