Judging from what you said, you already know that your cassette outputs have to be physically connected to the Line In of your PC's audio card.
I would very highly recommend Audiograbber, the only freeware you'll ever need for this purpose. Use it to encode the music being output from your cassette deck to the PC.
Once you install this software from:
http://www.audiograbber.com-us.net/ open the software and click on "MP3" after checking the box below it. Set the slider to the MP3 quality you want. It used to be that you had to explicitly place a Lame Encoder file in the directory, but I believe this is now automatically done during the installation (if you find that the higher bit rates are not showing up, drop me an email at: musicollector at gmail dot com)
Go to File | Line In Sampling.
Click on Mixer. Set your output volume such that the VU meter reads at the border or below the red section. Give it a name in the window.
Cue up the song, hit the Play button (the triangle). and start your music Your music will start encoding.
Once you complete this, install a very good software for burning CDs. I recommend CBurnerXP found at:
http://cdburnerxp.se/downloadOnce installed, you can use it to burn the CD. I recommend using two separate software for encoding and burning.
Hope this helps.
Harry
http://harry.cckerala.com