Well I think that the first place to discover how to develop in Genesis is the StudioPress platform itself. It contains a lot of information on how to move your first steps with this framework.
You have to know the Hook system of WordPress because Genesis it uses them extensively and is able to optimize lot of its codebase because of it. Another WordPress important knowledge to have is the child theme logic that you have to know before you can call yourself a Genesis developer.
If you need some video tuts you can check the new course in Lynda.com of Carrie Dills based on How to create a Genesis Child Theme where you can understand better the use of hooks and child themes.
After that you have to start and create some websites and learn how this framework plays with other solutions.
Hope this was helpful and don't hesitate to ask follow up questions ;)