Go to Settings > Themes > edit current theme
Click on the JavaScript tab
Paste your JavaScript in the area below
Save and Publish your theme
NOTE: JavaScript added should NOT include the opening and closing <script> tags.
For example:


Go to Settings > Themes > edit current theme
Click on the JavaScript tab
Paste your JavaScript in the area below
Save and Publish your theme
NOTE: JavaScript added should NOT include the opening and closing <script> tags.
For example: