What operating system do you have?
I'm not sure since I just got this computer like yesterday but I believe it's windows 8.1
OK, with windows 8.1 the apps are not automatically on the start page. At the bottom of the page you should see a downward arrow. Click on that to bring up all the apps installed on your computer. You can right click on photoshop to pin it to the start page or the desktop taskbar. In any of these places you can click on it or double click on it to run photoshop.
If you do not see photoshop listed under the adobe apps in the all apps page, then odds are it is not installed or was installed incorrectly.
If you need more help let us know.