The next screen should have a Screenshot icon listed.
You should now see a box with a white circle in it on your screen.
You can move this box around anywhere on your screen. When you press this button on your screen, your device with take a screenshot. However, if you have more than one icon you have set up in you Customized Top Level Menu, when you press the button, a box will pop us showing you all of the icons you have in this Customized Top Level Menu. For example, I added Notification Center and Control Center. So now when I press the button, I see the following options and can select any of them: