Change - render - environment (to different colour) and then if you see that half is white and other half is your chosen colour then you must change also the color in Brazil renderer settings (dont remember).
Man dont be funnyguy, search for proffessional Blender renders. Every renderer has its best renders. We all are making .... together compared to proffessional dudes And its not quite right too like we others have too. Window glass should reflect the nature on the other side but for that you need to make HDRI etc.