If it came with software, install that -- if not and it's Windows 10, there is no native DVD playback - you can use a free player like VLC Media Player, or purchase something like PowerDVD from CyberLink, or a DVD codec for Windows Media Player.  If you're looking to play blue-ray DVDs, make sure whatever you purchase supports blue-ray -- VLC does but will not play all blue-ray discs.  For that you'll need the full CyberLink suite.