To take a screenshot, below are the steps.
For Windows:
Press the Print Screen key on your keyboard. It may be labeled [PrtScn].
Open an image editing program, such as Microsoft Paint.
Go to the Edit menu and choose Paste.
If prompted to enlarge the image, choose Yes.
Optional: Use your image editor’s crop tool to crop out unnecessary portions of the screenshot.
Go to the File Menu and choose Save As.
Navigate to the folder where you want to save the image.
Type a file name for the image.
Select a file type.
Click the Save button.
For Mac OS X:
Press Command-Shift-3. The image is saved on the desktop.