Hello, if you do not give us more info, for instance what version of Windows or Mac Os you are running, we won't be able to help you.
(Some here might consider themselves gurus, but I doubt about their mind-reading abilities )
You did download it. Did you install it? go to your downloads folder, and run the installer.
then you will find Photoshop in your applications folder, start menu, or start Page on windows 8.