From the part 1 link above

Connecting a cassette player to a PC isn't difficult. Most hi-fis with built-in tape decks and standalone cassette players have a headphone socket and many hi-fis also have a stereo line output socket and either of them can be used. Virtually all PCs and laptops have a 3.5mm minijack stereo line input socket, so to connect your hi-fi or tape player to your PC you will need a stereo phono to 3.5mm stereo minijack or stereo minijack to stereo minijack cable. These are very widely available from electrical and electronic retailers, usually for less than five pounds. By the way, there's no point spending more on super hi-tech cables with gold plated plugs, it won't make an iota of difference in this particular application (or most others for that matter, but that's another story...).