If you havenever use Photoshop you have a huge learning task in front of you. I woul suggest you do a web search for Photoshop Beginners tutorials.
Well we can't have you becoming more harried.
What operating system are you using?
Have you installed the Desktop Application manager that has an icon like this:
And when open to the Apps tab, looks something like this
This is where you install Photoshop CC from. If on Windows 7, you'll find find the Photoshop icon in Start > All Programs. If Windows 8.1, got to Start screen and start typing 'Photoshop'. If Mac, I have no idea.
You'll find a long list of video tutorials on how to use CC here