Hi there,
I recently download Unity version 5.3.1.f1 personal edition as a complete beginner, and while trying to follow on with the “Roll a Ball” tutorial on the Unity website, I found myself immediately stuck because I had no default skybox or sun in my new project as the tutorial said I should. I was able to locate the skybox settings in the Lighting window and add the default skybox, but when trying to add a sun it said I had none at all. Also my GUI looks very different to the one in the tutorial if that helps, mine is grey and their one is black. Thank you for any help