I have never used any version of Lightroom before so decided to download a trial version from the Adobe main site. It appreade to download and installed correctly. On oepening the program it went staright to a main screen offering Library, Develop, Sideshow,Print,Web. Both Library and Develop seem to work correctly but I cannot switch between Library and Develop. Pressing D does nothing. As I am completely new to this I may just be stupid and have missed something. Can someone kindly offer some help please ?