Plug in the mini jack stereo audio cable 3.5mm to the "headphone" or "line out" jack on the keyboard. You can buy the cable cheaply at an electronics store.
Plug the other end of the mini jack stereo audio cable 3.5mm to the "line in" jack on the back of the computer.
Open a sound-recording software program. If the computer does not have a sound-recording program, you can find a free one to download online. Follow the install instructions and open the program.
In the audio recording program select "line in" as the main input source.
Click "record" in the audio program and the program will begin to record any input from the Casio piano, keyboard or other music player. You may need to adjust the input volume from either the keyboard or the audio-recording program.
Create beats. All models of Casio keyboards and pianos make creating a beat or drum loop a relatively simple process. On some models there is a "drum machine" keypad. Play it with the keypad and compose a beat. Each key on the drum pad will correspond to a different drum/percussion instrument. Reprogram the drum pad using the percussion instrument library on the keyboard or piano. On some versions of Casio products the keys themselves will be the drum pad. Using the instrument selector, select "percussion" or "drum". This will turn all the keys into different percussion instruments. Compose the perfect beat and record.