You do the same things as you would download something from YouTube using Windows. You find the video or music on youtube you want to download and use a converter. I always use
Notube Converter. I think this is the best one because there is a variety of possibilities for downloading and are the best qualities for videos and music. You have to copy the link from YouTube and after that put it in the converter. You have to choose the quality or the format and then just download the file. This converter also works and on mobile phones, I use it to download music.