I think there is a mobile app you can use, but otherwise you should just be able to load up the Ticketmaster site on your phone (if that's where you get them). Once you purchase the tickets, they provide you with a QR code on your account that they scan to let you in. You can keep all the tickets on one phone and just tell them you have multiple, and they'll just scan each one individually. I'd recommend pulling them up ahead of time just so you don't get stuck having to login. Pretty smooth process in general, I've done it plenty of times.