I hate doing those things although I do like listening to other peoples.
Normally you put down who you train with, your job, where you qualified, any other good wins previously and you could put down about Patrick's successful show career.
you only need to write a small amount - they only have the time before you enter at A to read it out so dont write an essay. just a line about what you and horse do, any other recent successes and anything interesting/unusual about either you or the horse.