For iOS devices:

1. Press the Power and Home buttons at the same time.
2. Hold them for a couple seconds and let go.
3. Open your Camera Roll photos, which is where screenshots are automatically saved.

For Android and Amazon Kindle devices:

1. Press the Power and Volume Down buttons at the same time.
2. Hold them for a couple seconds and let go.
3. Open your Photo Gallery, which is where screenshots are automatically saved.