Taking a screenshot on a PC is a more complex problem depending on which version of Windows your machine has installed.
For a PC running Windows 8 or better
To capture a screenshot and save it as a file, press the Windows logo key +PrtScn. The screen will dim for a moment when the screen is copied and saved as a file in the Screenshots folder (which is in your Pictures folder).
To capture a particular screen, tap or click the window you want to capture. Press Alt+PrtScn to copy the window into memory. You can paste it wherever you like.
For a PC running Windows 7 or Vista
Press PrtScn to copy the window into memory. Open Photoshop, or any image editor of your choice and start a new file. Paste the screen shot into the new file. Edit and save.