When you pee, and then try to stop the flow, you should feel a squeeze, right below your waist line, somewhere near the penis, obviously.
Now try to sit somewhere in your home, naked, and watch some porn until you are fully erect. Now let your penis rest on your belly. Then, try to reproduce that slight squeeze, try to imagine you’re peeing and “stop” the flow. You should notice your penis jumping up a bit, maybe half an inch, maybe more, that is the muscle that you practice when you kegel.
If you’re up to it, try to put your hand inside your buttocks.. I know it sounds weird and disgusting, and you don’t have to do it, it just might help you find the muscle.. So do it in the shower or something, and then try to do a kegel - “stop” the flow - and you should feel your buttocks slightly squeezing against your hand.
But bear in mind, the muscle you do kegels with is NOT the muscle you use when you go to the toilet, empty your bowels, so to speak.. It is a different muscle.. With just a bit of practice and self-awareness you can distinguish them quite easily.
For more information, there are a couple of useful guides here in this site.
Good luck.