After the iPad is set up, and each time you press the power button or Home button, a Slide to Unlock control appears. Drag your finger left to right along the slider to advance past the opening screen.
Once powered on, the iPad rarely needs to be turned off. Instead, when you’re finished using it, press the power button once (without holding it) to put it into a low-powered sleep mode.
The iPad automatically goes to sleep after five minutes of inactivity to conserve battery power. You can change that amount in the Settings app by tapping General, then Auto-Lock, and tapping a time duration (1 to 5 minutes, or Never if you want to always put the iPad to sleep manually).
To wake the iPad, press the power button ...