Can someone explain the .dmg file to me please. Whenever I install something now I obviously get dmg files instead of executable files. After I have installed the program then delete the .dmg the programs wont run? How can I maximise a window such as safari? When I run an application why does it appear on my desktop in the top left corner? Sorry for the simple questions - I've used windows for 15 years, and a mac for a day now.