Purchase a stereo 1/4" to 1/8" audio adapter cable from your local music or hi-fi stereo store. The cable should have two male 1/4" audio connectors on one end and a single male 1/8" audio connector on the other.
Set your MPC2000 up next to or close to your computer. Plug in the power cable and load up the sample library you wish to use off of the built-in floppy drive.
Insert the right-channel 1/4" connector into the right-channel audio-out connector on the MPC2000. Insert the left-channel 1/4" connector into the left-channel audio-out connector. Plug the 1/8" audio connector at the other end of the cable into the "mic" (red) or "audio-in" (green) port on your computer.
Start your preferred sequencing or recording software. This can be any software that will record audio, from Apple's GarageBand to Avid's Pro Tools. Start a new project by selecting "New Project" from the file menu, then create a new audio track by selecting "New Track" from the Track menu.
Press the record button in your sequencing/recording software to tell the computer to start storing the audio you put into it. Play your beat or song on the pads on the MPC2000. The audio will be transferred through the adapter cable, into the computer, and stored on the hard drive. When you are ready to listen to your track, simply stop recording, then press "Play" to play back the song or beat your just recorded.