Follow the steps -:
• Open all the apps and windows you want to include in your screenshot, and arrange them just exactly the way you want to see them saved.
• Press Command + Shift + 3 all at the same time.
• You’ll hear a camera click sound, and your screenshot will appear on your desktop in.PNG format, with the title Screen Shot [Date + Time].
• Double click on the screenshot to open and share it with Preview. Right click and choose Open With, or drag and drop it, to open and share it with another app.