I have a question about my jumping horse

ok, well i have a jumping horse that is pretty young. he is jumping 3'3'' courses and i love him except for one thing, well kinda. well, he iss the kind of horse that really takes you to the jumps. he will have a good steady canter, then a few strides before the jump he gets really fast to go to the jump. then after the jump he goes back to a steady pace. i know that this is good, but i was wondering if anybody knows and can tell me how to "check" a horse? i see people do it all the time in videos when jumping their horse like when they kinda pull the reins and the horses head lifts? i was wondering how to do that