The method for taking a screenshot varies depending on which operation system you are using, but they follow a similar process. Once you've taken a screenshot it will save to your computer, this can then be included as an attachment to your emails.
To take a screenshot, hold the Windows key and then press the Print Screen key.
By default, Windows screenshot are saved to the Pictures > Screenshots, folder.
To Take a screenshot hold down the Command + Shift keys, then press the 3 key
By default, Mac screenshots are saved to the Desktop and have a name such as 'Screenshot 2019-06-20 at 16.10.06', indicating the date and time the screenshot was taken.