Play different music in separate rooms

Hit the rooms tab in the navigation bar, select the room you want then hit the browse tab and select the music you want to play in that room.

Then repeat for each room you want to play music in.

Remember - current app if your on now playing screen for one room ..... swipe down. You'll get the nav bar at bottom. Then as jgatie said ... pick a room from the rooms screen then search for what you want to play in that room. Use the room bar at bottom to see all rooms and what is playing on each. Click on room you want to control.