How can I backup my iPad Air?

Connect the iPad to your computer and follow this article:

iOS: Back up and restore your iOS device with iCloud or iTunes

Use iTunes

You can use iTunes to back up and restore your content on your iPhone, iPad, or iPod touch. Note that iTunes and iOS do not support installing backups of newer versions of iOS onto devices using earlier versions of iOS.

Back up

To back up the content on your iOS device, follow these steps:

1. Make sure your computer has the latest version of iTunes.
2. Connect your iOS device to your computer.
3. Choose File > Devices > Back up.
   If you're using iTunes 10.7 or earlier, right-click the device from the list and choose Backup Now.

You can also back up by syncing your iOS device with your computer. When you use iTunes to sync, backing up is the first step.