As one who downloads songs from the Internet onto cassettes, I will be eagerly awaiting answers to your question, since I would like to become more adept at producing digital media.
cassettes??
Jeff mentioned Audacity. That might be what you need. Freeware open source and frequently updated. There's a bit of a learning curve. I am no expert, but I can get what I want, which is mp3 or wav files from my recordings. Documentation for Audacity is excellent - tutorials and whatnot.