Download an audio program, such as Audacity or AVS Audio Editor, to record your music and convert it to an MP3 file. Audacity and AVS are free to download (see Resources below).
Rewind your cassette tape to the point where you want to begin recording. Connect the 3.5 mm cable into the cassette player's "Line Out" jack. Connect the other end of the cable to the "Line-In" or "Microphone" jack on the back of your computer tower.
Open your computer's volume mixer settings. Make sure the "Line-In" volume is not muted or turned off.
Open your audio editing program and start a new recording. Simultaneously click "Record" on the program while pressing "Play" on the cassette player.
Save the file as an MP3 when it's finished.
Insert a blank CD into your disc drive. Most CD burning programs will automatically run when a blank CD is inserted. If not, use your Start menu to access your program.
Burn the MP3 file to the CD.