The “Custom Code” option is located within the Appearance > Woffice Theming Options > Custom Code Options.
Below is a screenshot on this:
Various fields are present here that include;
Custom CSS: Here you can fill in any custom CSS that you intend to add to your websit.
Custom JS: Within this section you can add custom scripts that you intend to have on your website.
Footer Script: This field is more preferrable for custom scripts that are ad specific such as Google Analytics. Note that you will need to wrap your code with <script></script> tags.