Follow these steps to "Harness your Website" on your Joomla
Step 1: Log in to your Harness Admin Dashboard
Step 2: In your "Settings" - click on the "Website Code" tab (or Click Here)
Step 3: Copy the "Harness Code"
Step 4: Log in to your Joomla Admin Dashboard
Step 5: In the upper menu, click "Extensions", select "Templates" and click "Styles"
Step 6: Identify your default template (it has a star next to it) and click on its name on the right side.
Step 7: Open the "index.php" file in the left menu
Step 8: scroll to the bottom of the editor and paste your Harness code just before the </body> tag
Step 9: Click "Save & Close"