Zouhar

Hi, I need separate two parts of picture by Magic Wand,then change colors and finally put these parts together again ( I need change blue snow on winter picture; sky is O.K. ). I tried it using Layers,without succes.I don't understand purpose of Layer window on right side down and small window on right side up.Why they are different ?Could You explain to me step by step what to do ( I am beginner )? One more question : how cancel tool,which I have choozen ? Thanks.