the easiest (built in) method is to use sound recorder.
the only specialist kit you need is a two ended male-male 2.5mm audio lead ... about �1.00 from almost any electrical shop that sells earphones
..... connect earphone socket of tape player to audio in of pc ... and play - record the tracks using sound recorder
(the most technical thing you need to do is adjust the volume
the next simplest (and better) is to download audacity (freeware)
http://audacity.sourceforge.net/
you still need the m-m audio lead.
play using tape - record to mp3 with audacity
edit if required