Download and install Audacity, if you haven't already. (See Resources.)
Connect your computer to your cassette deck using the RCA to 3.5 mm cable. The 3.5 mm end should be connected to your computer's microphone input and the RCA end should be connected to the Line Out holes on the cassette deck.
Open "Preferences" in Audacity and change the "Output Device" to "Microphone."
Lower the input volume. This is the volume bar labeled with a mini microphone logo.
Press "Record" on Audacity and "Play" on the cassette deck. When the tape finishes playing, press "Stop" on both Audacity and the cassette deck.
Click on "File" and select "Export as." Name your file, choose an export location, select "MP3" from the file format drop-down list and press "OK." Note that in order to export as an MP3, you need to install Lame, a plugin for Audacity (see Resources.)
Open your exported file with iTunes.
Enter the name of your MP3 into the search bar on iTunes. Once your track appears, click and drag it to the side of iTunes to create a playlist.
Rename the playlist and insert the blank CD. Right-click on it and select "Burn Playlist to CD."
Select "Audio CD" and press "OK." When the CD is ready for use, iTunes will alert you.