The Source Panel is the JCE opening screen. Here is where you put the source you want to obfuscate.
You can eigther paste in the code as usual using [ctrl]-v, the popup menu or load the code from a file.
The Open button bring up an fileopen dialog where you can choose to open the HTML or JS file you want to get obfuscated.
The Next button will take you to the Control Panel
where you can choose how to obfuscate.