For iOS Passbook:
Once you access your digital tickets you will see the "Add to Passbook" button:
From your iOS device or computer, just click that button and the tickets will appear in Passbook. If your order contains more than one ticket, you MUST add each ticket individually. For more information on using Passbook visit Apple.com
Tip: If you are purchasing tickets for friends you can forward them their ticket in iOS7 via AirDrop, Text, or Email by clicking the actions icon when viewing the ticket (You will want to keep track of what ticket you are using and which one you are sending them).
Here is a link to Android Passbook apps. Choose one that you would like to use and then you can save the digital ticket to your smartphone. From there, you can present the digital ticket on your phone at the venue's box office and they will be able to scan in your ticket.