Go to www.addsearch.com and sign up with your WordPress website address and email. Log in to your WordPress site. Select Plugins and click Add New. Search for addsearch, click Install Now and select OK. Open the confirmation e-mail, and from the bottom copy your Site Key. Go back to your WordPress admin interface and to the AddSearch plugin. Paste the Site Key in Settings → AddSearch and click Save. Select whether you want to use search-as-you-type functionality (default), or more traditional separate results page and click Save. Go to Appearance → Widgets. Drag the WordPress native Search Widget to your preferred widget area. If your theme has search somewhere else, it will automatically be replaced by AddSearch. You’re DONE!