Download and install the Audacity software program if you haven't done so already. You can click the link in the "Resources" section below to take you to the download site if you have yet to install Audacity.
Connect your 1/8 inch to 1/8 inch audio cable from your cassette player's "Line Out" output jack into your computer's "Line In" input jack. If your cassette player doesn't have an output jack labeled "Line Out" you can use the headphone jack. Similarly, if your computer doesn't have an input jack labeled "Line In" you can use the microphone jack.
Click the "Start" button in the bottom right-hand corner of your computer screen. Highlight "Programs," then "Accessories," then "Entertainment" and finally click "Volume Control." Begin playing your cassette tape to make sure it's coming through your PC speakers. If you don't hear anything yet, adjust the "Line In" volume under your "Volume Control" window. If you don't see a "Line In" setting, click "Options" followed by "Properties." Then click the "Recording" tab. Make sure "Line In" is selected and then click "OK."
Open the Audacity Music Editor program now. Underneath the "Pause," "Play," "Stop" buttons and so forth, there should be a little microphone icon. Be sure that the "Plus" and "Minus" volume bar next to the microphone is turned at least halfway up. Also be sure that the pull-down menu located next to the "Plus" and "Minus" volume bar is set to "Line In." Play your tape and adjust the input volume levels until you get clear sound without "buzzing out" or hitting loud spots that cause the sounds to flatten.
Rewind your tape to the very beginning and press the red "Record" button located near the top of the window. Then press "Play" on your cassette player. Let Audacity record the whole side of the tape and then press the "Stop" button when the tape is done playing. Don't worry about leaving extra space at the beginning or end of the tape, as this can easily be removed.
Highlight any empty space at the beginning and end of the track by clicking and holding down the cursor and then dragging it over the empty space. Click "Delete" to remove any extra space that's been recorded.
Select the entire track by clicking "Edit" and "Select All." Then click "Effect" from the toolbar at the top of the window and select "Normalize." Make sure both boxes are checked and then click "OK." Select the entire track again and then select "Effect" followed by "Noise Removal." This should take care of much of the hissing that came through when you recorded.
Export the entire file as a .WAV file by selecting "File" followed by "Export as .WAV." Select your computer's Desktop as its final destination for easy access. You now now use your CD/DVD burning program of choice to put your exported .WAV files onto a CD.