This question has been asked many times in this forum. Some of these questions referred to recording vinyl to CD - but the process is exactly the same. Do a search and you should get lots if information.
Essentially what you need to do is connect your cassette player up to your soundcard and record the cassettes to .wav files. Then burn the .wav files to CD.
Here is a quick overview: I assume you have a home stereo system with a cassette deck. The receiver should have some type of "line out" or "aux out" connections on it. Connect the cassette deck to the receiver, and then connect the "line out" connections on your receiver to your sound card.
The line out connections on the reciever will most likely be two RCA phone plugs (left and right). The connection on your soundcard is most likely 1/8" stereo miniplug. To make the connection you'll need a Y cable with two RCA plugs on one end, and a 1/8" stereo plug on the other. You might need some adapters to do this, but you can get everything at Radio Shack. Just tell them what you are trying to do.
Once you have everything physically connected, you will need software to record the .wav files. Roxio (Adaptec) makes a program called Spin Doctor that is designed for this purpose. It is part of their EZ CD Platinum package - however there are other programs that will do the same thing.
After you've recorded the .wav's, you can then burn them to CD using standard CD burning software (which is also included in EZ CD Platinum).
Do a search on "recording vinyl" and you should get lots more information. Here is one to get you started:
http://www.homerecording.com/bbs/showthread.php?threadid=20787&highlight=recording+vinyl
