Unfortunatly Backbone.js does not tell you how to organize your code leaving many developers in the dark regarding how to load scripts and lay out their development enviroments.
This was quite a different decision to other Javascript MVC frameworks who were more in favor of setting a development philosophy.
Hopefully this tutorial will allow you to build a much more robust project with great separation of concerns between design and code.
This tutorial will get you started on combining Backbone.js with AMD (Asynchronous Module Definitions).