Educate yourself on the basic structure of a beat (usually a drum pattern, bass line, percussion and strings).
Purchase a MIDI keyboard that allows you to record the music you play.
Buy a drum machine if you don't have a set of drums. Drum machines are desirable for their convenience and ease of use. Choose your drum sounds by scanning the entire sample browser to find samples you like. Start out with loops to get a feel for how the pattern should go (loops are drum and instrument patterns that are already created for you). There should be several loops under each instrument section on your drum machine. Add loops just as you would add a music sample to your beat.
Use a music software program to organize your beats. Music programs allow you to add effects to your instruments and alter specific parts of the beat. Attach your MIDI keyboard and drum machine to your computer and sync the hardware with your music software (read the owner's manuals for the hardware and software for further instructions on how to do this).
Decide what style of beat you want to create. Set your tempo around 90 if you want to create a slow beat; set it around 160 for a more upbeat tempo. Consider the instruments you're going to use: Hip-hop beats contain a great deal of bass, for example, while country has less bass and more guitar, and rock beats are usually heavy on electric guitars.
Find the instruments in your music program's music browser. You can also import instruments from your drum machine. Bring the instruments over to the music program's sample loader. Control the instruments and samples with your MIDI keyboard.