You need a stereo cable which has stereo jacks on both side of it and a software called Audacity.
Install and run Audacity, and select the recording source as "Line In".
Then connect the Audio(Headphone) Out of the Audio Player to Line In of your PC.
Then right-click the Speaker icon and click "Open Volume Controls". Here go to Options> Properties and clikc "Recording" and then clikc OK. Then in main window check (or uncheck if the option is "mute") Line In and adjust it's volume slider to max.
Then click "Record" in Audacity, after this reduce the bass, treble and any other effects in the Audio Player to zero, and play the song from start of the Tape.
After the recording, select the "empty" portion of the recorded sound and, then go to Tools> Noise Removal and clikc "Get Noise Profile".
Then select all the recorded sound and go to Noise Removal, and there reduce the slider to a "lesser" position and clikc "Remove noise".
*audacity.sourceforge.net/
Do a trial run before recording so as to get the noise free recording, if there is excessive noise, reduce the volume in the Audio cassette player.