There's lots of videos on youtube that can show you how to properly sex your snakes, whether you want to try the popping or probing technique. Probing will require you to do get a kit of specialized tools and isn't as accurate as popping, but it's can be easier to do and requires less technical skill. If you're unsure if you can do either yourself, do as Reinz suggested and find a person near you who has some experience with it and can either do it for you, or show you how to do it yourself while they supervise. Once you've learned proper technique, it gets easier with practice.