There are a few different ways you can sing karaoke on a laptop. One way is to find karaoke versions of songs online and play them through your computer's speakers. You can also use a program like VanBasco's Karaoke Player to play karaoke files. If you have a karaoke microphone, you can connect it to your laptop and use it to sing along with karaoke tracks. You can also use your laptop to record yourself singing karaoke, either by using the built-in microphone or by connecting an external microphone.