You can also add a Google Search Field to your website which will allow your viewers to search your site for something. You can add the search field to the Header or Sidebar on your website.
Please note: This is a Search function is a Google feature which means that the search results get displayed in a Google page and it will only produce results from your website (not the whole world wide web).

To add a Search Field:

Step 1:
Click on the Widgets Tab.

Step 2:
Click the Add to Sidebar/ Header' on the Search widget in either the Header or Sidebar, depending on where you want it to be displayed on your website.

Step 3:
Once enabled the widget will be displayed in blue. Press 'Remove from Sidebar/Footer' to remove the widget from your website.