The Pre-processing Region is specifically for running functionality before the DOM starts when a web page loads. Access to this may be useful if you want to initialize a database connection on your web page. For access to the Pre-processing Region please submit a request.
Once your request has been processed the Pre-processing Region will be enabled on your page as an Editable Region. You will find it at the top of the page in Edit mode.
Open the Editable Region and enter the Source Code editor by opening the HTML icon.
You may input your code in the dialog that appears.