The key to achieving a good quality render is to research a high resolution photo for your backdrop, then you have to open retrace assistance box and adjust the settings. open the edit box in the retrace section and go to adjust lighting, click on use sky. There are many other small tricks to achieving a good quality rendering however Chief architect still has a long way to go when it comes to being able to produce high quality HD renderings as the software does not have VRay capability which in my opinion is very unfortunate.