I you have an Apple TV (or a computer running Reflector) connected to your projector or TV, you can wirelessly project your iPad, iPhone, or iPod screen using AirPlay Mirroring. AirPlay will work from any Apple device (and some non-Apple devices), but the screen mirroring part doesn't work on some older devices.
To start, make sure you are connected to the same network as your AirPlay receiver (Apple TV or computer running Reflector).
Swipe your finger up from the bottom of the screen to access the Control Center. If there's an AirPlay receiver on the network, tap on AirPlay and select which device you'd like to AirPlay to.
Once you've selected an AirPlay receiver, you can turn on Mirroring if it's supported.
If you have AirPlay security enabled on your AirPlay receiver (either Onscreen Code or Password) you will be prompted to enter it.
When AirPlay is active, the top bar of your device will be blue, and you'll see the AirPlay icon at the top right.
When you want to stop AirPlaying, swipe up from the bottom again, tap AirPlay, and choose iPad.