When you are doing copy-and-paste, you might want to use an item that you copied earlier. Pressing "Windows + V" shows you the system clipboard so you can choose items that you have copied earlier.

You can take a screenshot in Windows by pressing the shortcut "Windows + Shift + S". Then, select the part on the screen you want. The selected part will be copied and you can press "Ctrl V" to paste it into your document.