Hi. Vocaloid is a voice program synthesizer. Here's the wiki: [link]
Here's a few beginner songs: World is Mine by Hatsune Miku: [link]
Triple Baka by Neru, Teto and Miku: [link]
And, the last one is Meltdown: [link]
From the Wiki, you'll find more songs and your way through Vocaloid.
I'm not sure if this person is active, so I'll just tell you. Have a nice day!