Please be as specific as possible.

On a Mac: To take a screenshot: Shift + Command + 4

drag to select a specific area hit spacebar to save the entire screen

On a PC: To take a screenshot: Windows Key + Shift + S

click the menu to take a rectangular, free-form, window, or full-screen capture click the preview notification to annotate and/or save
(Max 10 files, 200 MB per file)