First, you have to connect your tape player (external device in general) to the Line In input on your computer's sound card. Of course, the condition is that your tape player has a sound output (Line Out) or otherwise the whole thing with transferring recordings will not be possible. You will need a proper cable to establish the connection, so if you do not have one pay a visit to the local electronics store.

Ok, hardware is in place, now switch to software. With Claudio installed, start it, click MIX - Recording and make sure Line In is selected as the sound source for recording. After that simply click on Record button on Claudio's front panel to start recording, then start playback on the cassette tape player. That should do it and you should see the signal animation line on Claudio's front panel moving.

Finally, when you finish recording, you can export it from Claudio to WAV sound file (Export - Export Track To WAV) and use that file in software for burning CDs.

Notes:

• If the signal animation line stays flat then most likely nothing is recorded and you should check the cable and/or hardware involved and re-check which sound source is selected for recording.
• Do not try to make this work by connecting an earphone output on the external device to a microphone input on the sound card. The impedances are not matching and that might be harmful for the hardware or at least reflect badly on the sound quality.
• If there is no suitable output on your external device to connect it to your computer through a cable, the last resort is playback in front of a microphone, but that way you will be also recording all other sounds from the environment and the sound quality in general will not be good.