I would try to go to a local show and see if there is breeder there who would be willing to go through it with you and show you again. Also, there is a video that explains the technique. It's called: Dr. Mark Seward's - Determining Sex in Snakes. I haven't received it yet (just ordered it), so I cannot give you a good review on whether it is helpful or not. Here is the website I ordered it from though: www.ballpython.com. It is under "Available" - "Merchandise".
What are you planning on breeding?
>>Hello all,
>>I'm trying to figure out how to go about learning how to probe/pop snakes to determine sex. I need to learn, because I'm gonna be doing some breeding in the future, but i'm afraid of hurting my animals in learning the technique. I've seen it done a few times, but never done it myself. Can anyone give any advice?
>>Thanks
>>-John
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Amber 
1.2.0 Ball Pythons - Tucker, Trinity, & Tyler
1.0.0 Snow Corn - Aiden
0.1.0 Pueblan Milk Snake - Marishka
2.1.0 Dachshunds - Dakota, Montana, & Cheyenne
5.0.0 Ferrets - Tigger, Bailey, Cody, Keyta, & Bandit