Greetings, respective SugarGuru!

I'm a new to SugarCRM, but I'm very excited about it. I'm trying to create a "create case" button in the Cases popup-window, but i'm stuck at the very beginning. Exploring the structure stopped on finding no "Popup_picker.html" at modules/Cases folder.

Please, show me the way, and I will try to do it by myself!

Thanks in advance,
Sencerely, Dmitry.