To transfer cassette tapes to digital file, first you need a decent cassette deck. We strongly recommend using a cassette deck rather than a cassette to digital converter. You want the best quality possible when you do the transferring and even an old cassette deck is much better than cassette converters when playing tapes.
To get the audio signal into your computer, use a RCA to 3.5mm cable. Connect the red and white plugs into the back of the cassette deck labeled REC. Then plug the 3.5mm end into your computer audio in port. Most desktops have an audio card that have an audio in port. If you want to use a laptop, then you’ll most likely need an external USB audio card DAC or adapter to capture the signal.
The last thing you’ll need is software that can record the audio coming into the computer. We recommend Audacity. It’s free to use and works really well. Set your source to the audio card in signal and press the record button. You should see the timeline move the recording waves on your computer screen. Once you are done, trim the empty parts and export it as a WAV file if you want it uncompressed. If you also want individual tracks from the captured file, you can do that by labeling the beginning of the track on the timeline and export the capture as multiple files. Here is a tutorial on how to label and export multiple files.
Happy cassette tape converting!