Use a metronome to help keep you in time. Choose a slow timing such as 60 beats per minute to build your muscle memory.
Strike the kick drum starting with your right foot and alternate strikes between your feet in eighth notes performing a normal double kick pattern.
Incorporate the hi hat into your beat. Strike the hi hat with your dominant hand using quarter notes while continuing to play the double kick eighth note pattern. The hi hat should strike on every other kick drum hit following your dominant foot.
Use your non-dominant hand to strike the snare drum in the pattern of eighth notes. The snare hand should hit along with every kick drum hit.
Practice your blast beat at slow beats per minute until you can play the blast beat playing 32nd notes with your feet and snare hand while playing 16th notes on your hi hat or crash cymbal. The more you practice, the faster you will get.