The house has a "Whole House Audio", meaning there are speakers in many rooms and all can be setup to play the same or different music. This system is build upon the Sonos equipment platform which uses an phone App to control it. Get that and download it. Many things will be intuitively obvious - meaning they aren't, but are the same as most other Apps. There are also Apps for some computer systems.
The basic control is to select the room you want to control, then select a source of audio for that room. When selecting a room, you also "group" multiple rooms so that they all get the same stream and are in sync.
Music can either be streamed from online sources, like Tune-In, or Pandora, come from things you have on your phone, or come from the "music server" which is just a hard-drive full of music connected to the network. As with most music interfaces, you can setup a playlist to keep the music going all night long.
The most frequent problem with the system is that our power goes out, but the amplifier for the system doesn't turn back on by itself. The amplifier is located in the equipment closet across from the bottom of the stairs, slightly to the left. When you open the door, immediately to the right, inside, is a rack of the Sonos equipment. At the very bottom is the amplifier. It should have a long row of blue lights when it is turned on. If there is a long row of red lights, it is off. Just press the button on the left side to turn it on and you are good to go. If there are no lights at all, power is probably not getting to the rack - you're on your own to figure that out.
This is usually a networking problem. To control the Sonos, make sure you are connected to one of the non-guest WiFi access points or using a directly wired ethernet connection into our network. The Guest WiFi is prohibited from connecting to other devices within the house, so cannot control Sonos.