Set up the iTunes Remote app for iTunes on Mac
If you have an iPod touch, iPhone, or iPad you can use the iTunes Remote app to control your iTunes library from a distance. iTunes Remote is available as a free download from the App Store.
Pair iTunes Remote with an iTunes library
Before you can use iTunes Remote, you need to pair it with the iTunes library (or libraries) you want to control. Your device and your computer must be on the same wireless network.
Disconnect your iOS device from your computer, if it’s connected.
On your device, tap Remote on the Home screen.
Tap Settings, then tap Add an iTunes Library.
A 4-digit code appears.
In the iTunes app
on your Mac, click the Remote button 
near the top left of the iTunes window. Type the 4-digit code.
iTunes pairs the library on your computer with iTunes Remote on your device.
Pair iTunes Remote with your Home Sharing network
If you have iTunes Remote 2.0 or later and Home Sharing is turned on, you can set iTunes Remote to pair automatically with any of the iTunes libraries on your Home Sharing network. See Import media using Home Sharing.
On your iOS device, tap Remote on the Home screen.
Tap Settings.
Tap to turn Home Sharing on.
Type your Apple ID and password, then tap Done.
Tap the iTunes library or Apple TV you want to control.