Totally Random

I found the PrntScr button!!

But it does nothin' when I press it... Vad är det som händer?

Yep, what Kaz said. ... I couldn't tell ya how many people tell me their prtscn doesn't work, since it didn't simply print it out when they clicked on it. They should have named it 'cpyscn' since that's what it actually does.

Where is this "clipboard" you speak of?

Dom, there's no physical location for the clipboard, it's virtual in that it's stored in the computers RAM. Basically your telling your computer to take a screenshot of what's showing on your monitor screen, and then you can paste that data into another program. Just right click and select paste while you're in Word, Excel, PowerPoint, Photo Shop, etc. ... The screenshot is generally saved as a PNG, JPEG, etc by default.

Whenever you use Ctrl-C your selection goes to the clipboard.
Similarly Ctrl-V copies from the clipboard.

So press PrintScr.
In Photoshop (or whatever) create new image at the same resolution as your desktop.
Then press Ctrl-V.
Voila!

Some versions of software let you skip some of those steps and create a new image directly from the clipboard. (It'd be under File> New>..from clipboard. Or perhaps Edit> Paste As New.) But the method above should work for all software.