I am trying to build my first widget, for use in the Configurable Map Viewer (CMV) and I want to start with something basic. I was wondering if there is a tutorial or a step by step guide to create a simple "Hello World" widget in the CMV application?
After briefly looking through CMV, it looks kind of like a wrapper for the ESRI/Dojo widgets.
I would suggest looking at ESRI's samples to get an idea of how those are implemented. Here is their information on creating custom widgets.
Then once you're comfortable with that, I would look at CMV's widget documentation and see how they wrap around existing ESRI widgets.
Somewhere along the line, you should probably get a good feel for how the widgets are used and constructed with CMV. After looking through a little of the basemaps widget configuration it looks like CMV takes JSON objects and implements them into a format that can be read into ESRI's JS API.
There doesn't seem to be a tutorial out there. However, it looks like user's have submitted their own widgets to the repository so it would be worth a look through their code to see what they're doing, too.