Visit a karaoke song download site (several legal sites are listed in Resources below). If you are interested in just audio files you can use to practice singing and have access to the lyrics for your song elsewhere, you can simply download karaoke versions in MP3.
Set up an account. All legal sites will require an account with credit card information. Songwriters still receive royalties for karaoke versions of songs, so it's important not to download karaoke tracks illegally, even though they aren't always performed by the band or artist who made the song famous.
Select your songs, then purchase and download them. If there are multiple file formats available, choose "MP3" for an audio-only file. Some karaoke sites will allow you to download a package of files. You will only need the MP3 part of the package.
Import the songs into your preferred music player. As regular MP3 files, the songs can be played like any other music track in iTunes, Windows Media Player, QuickTime or any other popular free MP3 player.
Download karaoke CDG software. CD+G is an industry-standard for pairing karaoke audio with scrolling lyrics in video. Downloading software (see Resources) will allow you to read lyrics from your laptop screen while you sing. If you are hosting a karaoke night, you can also connect your laptop screen to a projector or television screen so other performers can see the lyrics while they sing.
Install the CDG software. Double-click on the downloaded package and follow the instructions for installing it to your hard drive. The instructions will differ depending on your laptop's operating system. Check to make sure the software is compatible with your operating system and computer specs before attempting to install the software.
Visit a karaoke song downloading site (see instructions for Audio Only above) and download CD+G files. These usually come in a zipped package containing an MP3 file, a CDG file and a MCG file. Your karaoke software will need all three of these to link the song to its lyric video.
Unzip the package. Right-click (control-click on a Mac) and choose "extract" or "unzip" to unlock the three song files so they can be loaded by the CDG software.
Import the song files to your CDG software. Instructions differ slightly for different software packages.