How to shave down there!!

Hey guys,
So I've tried a couple of times shaving down there and it always gets sore and kinda pimply and red spots down there . Am I doing anything wrong or is there anyway to make it better cause I really need to know. I'm 17 and a gymnast so it's important to not have hair down there otherwise that would be really embarrassing haha .
and I don't want to wax just shave , any help would be so good 
Thanks :)