Thank you to Erwin in a previous post I got to render an scene with 4 lights. But as you can see in the attached pic I still have 2 problems.
1 The interior is still quite dark I can't increase the intensity of the lights, otherwise they will burn the pic. I also put an general light behind the camera but it seems it is not enough.
2 The white walls on the background have some kind of shadows on their corners. I am rendering with Global Illumination in preview set up if I choose final set up, then disappears but I need almost 4 hour for this simple render, and I do not have the time. Any intermediate set up for Global illumination.
Regards