A mini CD or a mini DVD looks exactly like a regular compact disc or digital videodisc, except that it's smaller in diameter. Fortunately, that's the only real difference when it comes to playing a mini disc. These discs are designed to function the exact same way that their larger counterparts do, which means that all you need to do is have the appropriate drive on your computer or a DVD player and you can play the mini disc.
Open the drive you're using for your mini disc and put the disc inside with the centre hole pressed over the tray's centre spoke. If it's a music disc, put it into a CD player or CD drive. If the mini disc is a DVD disc, you'll need a DVD player or a computer's DVD drive to play it properly. For this we'll assume that you're using a computer's drive and not a DVD or CD player.
Close the tray. Left-click the "Start" button and then left-click the "Computer" option that comes up. A window showing you all of the components on your computer should come up, including the drive with the mini disc inside.
Double-left-click the drive with the mini disc in it. If the disc is a DVD disc or a CD, it will attempt to start playing the content on the disc using the appropriate program such as Windows Media Player.