Press the add button under 'sources' in the main window. Press that button to add a source, or right click it to add sources. It appears you deleted your default screen capture source. Guess I'll have to make some sort of a wizard to help people out with this if it doesn't detect any sources. Not sure why you deleted them -- if you did delete them. There might be a bug here, because I don't see any scenes either. I'll investigate.
In the mean time, add a scene (left list on the bottom left of the main window), then add a source (bottom center of the main window).
