FINDING Royalty-Free Music
If you choose to use music in your video, you can't just download a Drake track from YouTube. You need to find music that is ROYALTY-FREE and LICENSED FOR FREE PUBLIC USE. There are many websites out there that host works that are available to download and use in your videos. These tracks are often made available under a CREATIVE COMMONS license. Some licenses will require you to ATTRIBUTE the author in your video. See the Creative Commons website FAQ below for more info.
Creative Commons has provided links to some sites that host music that you can download and use for your videos.
freemusicarchive.org is a good one.
Once you find a track you like, check the license and attribution info. Copy any relevant author/publisher info that you will need to cite in your video.
Upload your audio track to Google Drive.