Simmy, if you are on a Windows system, click on the Start button, then on All programs, and scroll up or down the list.
Or type Photoshop into the seach field after clicking on Start.
If you are using Windows 8, then I am afraid I don't have a clue, but the answer is nevr more than a Google away
http://www.dummies.com/how-to/content/how-to-start-a-program-or-app-in -windows-8.html