1) You will need a "Stereo patch cable, with a mini-jack male on each end". This sounds technical but it is not, When you look at a set of headphones made for walkman equipment, that end is a stereo mini-jack male end (notice it has TWO black bands on it). If you have only one black band it is not a stereo cable (two channels, left and right) it is a mono cable (one channel).
You want stereo, especially for music, because sometimes the musicians use the left and right channels for different effects in their music. I think Walmart has this but Radio Shack definitely does.

2) On the back of your computer where you plugged in your speakers, you will notice two more "holes" (called jacks). One hole is for a Microphone, and the other is usually a "line in". It probably won't matter which you use, both are inputs into the computer (so the sound goes from your cassette, into the computer). You can experiment with these. Anyway, plug one end of the patch cable (step 1 above), into the microphone input.
If you have a recording which is too loud when you finally get it on your computer, and the record levels cannot be set, then make sure you use the “line in” on your computer’s sound card because you can lower that high volume recording as it comes into your computer. Most commercially recorded music will not be this way, it is nearly always from amateur recordings.

3) Plug the other end of the patch cable into your headphone output on your cassette device. If you need a bigger plug, then your cassette has a "Quarter inch jack". Walmart has this (it is a $5 pack of 5 connectors). Radio shack has this converter also.

4) Now you need the software to vary the input level of the signal from the cassette. On windows it is the sound control (in your task bar looks like a sideways cone). When you double click on it in the taskbar, you will see an array of "slide" switches. You are familiar with the volume, now you need to control the "Line in" or "Microphone" input level (whichever you connected the patch cable to). You will need to record (see next step) and then playback the song to see if your level was correct.

5) Now you need the software to record the actual sound signal from your cassette. I use Musicmatch jukebox plus (@$50 to be able to record), however I believe all versions of windows ship with a Sound Recorder (Start | Accessories | Multimedia | Sound recorder), Someone told me that the Windows Media Player does record, but I haven't found that to be true on my version. I am going to move to a program call Cool Edit which I downloaded from www.zdnet.com go to their downloads, and enter cool edit in the search box. Cool Edit allows modification of the sound signal in a number of ways. Most people will not need this sophistication, but if you wanted to “mix” two songs/sounds, then this is a good start.
In the end, all of these programs have the recorder portion of the program look exactly like a real cassette recorder would look. The red dot starts the recording immediately, the square stops the recording, the triangle pointing towards the right is the play, etc...
When you save your "file", depending on the program the default will be either MP3 or WMA. Most people use MP3 so you may want to always use this.

6) To burn the CD, your CD recording software (I use Nero from Ahead Software, Adaptec CD recorder is usually shipped with CDR burners) will offer you the option of burning a Data CD, or Audio CD, also others as well. Choose Audio CD. Then you can choose the MP3 or WMA files to record onto the CD. Your program will give you a "Start burn" button to begin recording onto your CD.
One note about CDs, they are not all created, buy Verbatim, 3M, or Imation, otherwise you may run into a time when someone cannot read the CD.
Finally, always play your CD when you have burned it. CDs don't always burn properly because the media is bad, in which case we call them "Coasters" as in coffee cup coasters. Besides using these as coasters, you can also superglue two of them together so the shiney side is showing and hang them where you don't want birds to land. The light flashing off the CD chases them away.

That's all there is.
Good Luck
-T-