Open your beat-making program and start a new project.
Decide what genre of music the beat will be for. Hip Hop beats can either be a slow and laid back tempo or quite upbeat while punk songs generally have a fast tempo. Tempo is measured in beats per minute and literally means how many beats the song has per minute. As a general guide, 120 bpm is fast, 100 bpm is moderate, 80 bpm is relaxed and anything less is slow.
Choose which instruments you want to use in your beat. Rock and Hip Hop beats use kick, snare and tom-tom drums, and hi-hat, ride and crash cymbals. However it is your song so add any percussive instrument you wish to add. You might also want to use unusual drums such as tambour, tabla or bongos for a different, exotic sound.
Program the instruments into the beat. Most beats are in a standard 4/4 timing which means there are four beats in a bar. In this instance this means that the kick drum is usually placed in the first and third beats and the snare is placed in the second and fourth beat. The hi-hat can act as a cohesive agent keeping the beat together like a metronome so place the hi-hat every two beats for a steady, repetitive sound.
Alter the beat once you've gotten a basic beat that you are happy with. This could mean dropping out a kick drum here or there to put emphasis on certain elements of the song. Likewise you might want to add a crash cymbal for the same reason or to signify the start of a new section.