You must have "Full Access" or "Limited Access - Website" permissions to add Google search.
Go to the Google Custom Search Engine.
On the Custom Search page, enter your website into the "Sites to search" field.
Enter the name of your website into the "Name of the search engine" field.
Click Create.
Click Get Code and copy the code from the gray box provided.
Return to your website and navigate to the page you would like to add the search bar to.
When logged in, go to Edit Mode.
Click Add Page Element and select the Code option.
Paste the code you've copied from Google and save.
Helpful Tip! It may take a few days for Google to crawl your site if you don't see your content right away. Additional Webmaster Tools with Google: Google adds new sites to their index, and updates existing ones, every time we crawl the web. If you have a new URL, CLICK HERE to direct to Google.