Find someone to teach you how, I think you're in MD, so I'd go up to HDG, everyone there is super nice and I'm sure someone would happily teach you how to properly do it.  It's not something you want to try just by looking at videos online.  My vet taught me how to properly probe, but I'm still a little nervous with it so I brought a ball python up to HDG last month just to have someone double check for me, like I said, everyone's super nice up there.

Go to Kathy Love's: CornUtopia.com

Bottom right hand corner look for 'Sexing Videos'

She gives a great demonstration and explains as she goes.

I hope this helps.

+1 Brittany. I had to watch someone do it in person SEVERAL times before i felt comfortable doing it myself.

Go to a proffesional before doing it yourself you don't want to risk injury to the snake

i agree, get someone to show you. Here is a scan i took of a page from the reproductive husbandry of pythons and boas. some names have changed and not everything is listed but it is a start.

I had such a variety of answers from another forum years ago and once I tried some of the "methods" I was dumbfounded when I finally decided to get a second opinion from my local vet.  They were extremely helpful in showing and walking through the process.  It took the intimidation and uncertainty out of the picture.

I know that when probing it is best to probe to the left or to the right to get more accurate measurements. For males, you will be able to probe further in as the hemepenes (sp?) are inverted in the tail. You probe from the cloaca towards the end of the tail.

Justin Kobylka has some great instructional videos for balls.  http://www.jkobylkareptiles.com/

Ralph Davis has some good ones too. Just look around Youtube for them.

depending on what you are trying to sex you might be able to find out how to sex that perticular species on you tube as well

Once you learn how to do it probing is very simple with most snakes.  The best thing is to get instructions from an experienced herper, and have them let you actually do it under their supervision.