First off, download some freeby sound recorder program. Audacity is good, although it's not very user-friendly for beginners. If you google "free sound recorder program", you should find a fair few hits.

Then get a 3.5mm-jack-to-3.5mm-jack cable (from your nearest electrical/PC/home-office store - if it's more than £5, find somewhere else). Stick one end in the cassette player headphone socket; stick the other end in the PC line-in socket. Turn the cassette player volume down to about 50% or so. In your sound recorder program, set it to record from the PC line-in, hit "record", and then hit "play" on the cassette player. Save the results as an MP3 - 256MB gives good audio quality.

This will *not* be crystal-clear hi-fi quality. But you're starting with cassette tapes, so you'll never get top quality anyway. This system is simple and cheap, and the recording quality will be limited more by the quality of the cassette than the quality of this hookup.

Graham.