Install a digital audio workstation on your computer. Make sure your computer contains musical instrument software such as Pro Tools, Reason, Cubase, Logic, GarageBand, ACID or FL Studio. If you cannot fit a professional digital audio program into your budget, use a free program that performs many of the same functions (see Resources). Just download the software (or purchase a software disc from a music supply store) and install it on your computer.
Record or input music into your digital audio program. If you plan to use your computer to play backing tracks, such as instrumental accompaniment without a live band, you must first save the accompanying music using your digital audio program, which enables you to play the music in real time at your live show. If recording from scratch, open the software and use the "Record" function to create your original music. If importing an already-recorded audio file, just drag the file onto the blank recording space in your software window and save your work.
Set up your computer keyboard to function as a musical instrument if you plan to use it as a digital MIDI controller. MIDI refers to digital note control, and a MIDI controller is any device that allows you to play virtual instruments on your screen. To designate your keyboard as a MIDI controller, just access your "MIDI" options, usually found in the "Options" or "Preferences" window accessed from your menu bar, and look for an option that reads "MIDI Control" or "Musical Typing." Certain programs, like GarageBand, contain this feature by default, while others, like Cakewalk, offer downloadable plug-ins.
Set up your virtual instrument. Decide the type of sound you want to play when keys are pressed by creating a MIDI track within your chosen software. Your track list, which consists of your individual recording layers, appears in the left column. To create a new track, locate the "New Track" option, usually appearing under the "File" menu at the top of your screen or under a specialized "Track" menu, also on the menu bar. When you select this option, a pop-up menu may ask if you want to create an "Audio" track or a "MIDI" track (sometimes called a "Software" or "Instrument" track). Select the "MIDI" option. When the track appears, double-click it to see your track options, and choose a virtual instrument from the list.
Connect your computer to a USB audio interface. In order to successfully transmit sound from a computer to a live speaker system, you must use an audio interface, an external sound card that connects to your USB port and contains jacks for instruments, microphones and speakers. Plug the device's USB connector into your computer's USB port, and plug the speakers into the output jacks on the interface. If you have additional instruments and microphones, plug those into the instrument jacks on the front of the interface.
Open your saved music projects using your digital audio software. If only using the computer for backing tracks, just click "Play" to transmit your music over your speaker system. If using your keyboard as an instrument, click your previously-created MIDI track in the left column and press "Play." As your backing tracks play (if applicable), you can add additional music notes by pressing the keys on your keyboard.