For Windows:

1. Select the Print Screen (PrtScn) key to capture the entire screen and copy it to the clipboard
2. Open an image editor (like Paint) or a document editor (like Word)
3. Paste the screenshot by selecting the Ctrl + V keys
4. Save the file if needed, then print it by selecting the Ctrl + P keys or selecting the print option from the menu

For macOS:

1. Select the Shift + Command (⌘) + 3 keys to capture the entire screen and save it as a file on your desktop
2. Select the Shift + Command (⌘) + 4 keys to capture a selected portion of the screen
3. Open the screenshot file and print it by selecting the Command (⌘) + P keys or selecting the print option from the menu