On your Windows Computer:
Hit the PrtScn button and the Snipping Tool should open up. Highlight the area you want to take a screen shot of, then select the appropriate option.
Copy will allow you to paste into the body of an email (this is what you should do if replying with a screenshot)
Save will allow you to save to a jpg file.
Email will open a new email with just the snip attached.
On your Mac Computer:
Take a screenshot of the entire screen: Hold Command, and while holding control, hold shift, then while holding both keys, hit the number 3.
Take a screenshot of a region or specific part of your screen: Do the same as above, but instead of hitting 3, hit the number 4. A little crosshair will appear where the mouse is. Click and drag the area you want to take the screenshot of.
Where do screenshots go? By default, they will appear on your desktop.
On your iPhone:
Hit your home button and power button at the same time. The screen will flash, and save the screenshot to your photos. You can then attach to emails, texts, etc.
On your Android:
This will vary by model, but typically it’s the same as the above. Hit the power and home button at the same time. On some, you can also swipe the side of your hand across the screen to take a screenshot as well.