Insert the red and white RCA cable jacks into the corresponding red and white output sockets in the back of your cassette deck.
Insert the mini-jack situated at the other hand of the RCA cable into the line-in socket on the back of your computer. Insert into the headphone socket if you are using a laptop computer.
Open your recording software, this program can be anything with a recording option, such as Reason or Windows Media Player. Select the "New Track" option. Set it up to record.
Play the tape you want to record in the tape deck. Adjust the levels on the recording software until the music is registered strongly on the level gauge but does not exceed the limit--indicated by the red bars at the top of the gauge.
Rewind cassette back to the beginning. Press "Record" on the music recording program. Press "Play" on the tape deck.
Save the recorded material to your desktop.
Click on the iTunes icon in your dock bar. Drag the recorded tape file into your iTunes library.