Click on the cassette to bring it to the boombox; it will automatically start playing. Press E to eject a cassette, it will automatically stop playing. Technically, you don't have to eject a cassette to put in a new one... but it looks realistic! Update 7/16/2017 - I wanted to add "Land of Confusion" by Genesis, but Scratch says it will exceed how big the project can be. So now I will not be adding any more music. Ether that or I'm being hacked by the Russians!