I'm guessing there a large number of listeners who don't even know what a cassette is. It's a little piece of plastic with a roll of tape inside which could record sound on it magically using magnetism. In any case lots of people have cassettes and want to get the music off of those because amazingly cars don't come with cassette players anymore.
There are lots of different ways to do this. I can recommend a lot of different tools but the one that most people use is a free tool called Audacity. You can get Audacity online. Just search for it. It's easy to find.
They make it easy to import the audio from the cassette and then break it up in the song tracks. Watch out for the track breaking up feature however, it's a little difficult to find. They call it "labeling a track". You want to look for the feature called "label" to create multiple tracks. Once you've done that you can easily export the audio and save it to a CD.