Pamdaga, this is very hard for me to explain how you find it and then squeeze it, but I will try.
The muscle is not the pc muscle. Very seperate. It is at the very bottom of where the spine ends in your ass.
If you try to imagine sucking water up through your ass that might help you locate it. Imagine you are sitting in a warm bath and now try and suck some water up your ass. I have never tried sucking water up my ass and don’t even know whether it would work but just imagine it was possible and try sucking as you imagine it.
Hopfully you will be feeling a certain small muscle contracting and squeeze near your anus and tailbone area when you try this.
What you are hopfully succesfully squeezing is part of this tailbone muscle but there is more behind what you should have been able to squeeze, actually right under the ending of the spine. Try and squeeze both that part aswel. Explore all those muscles that you can squeeze around that area and you will find it. You want to be able to squeeze all of it and not just the part you should have discovered by trying to suck with your ass.
Once you have discovered it all, you need to exercise it by squeezing it maybe 300 times a day to get your brain used to squeezing it and controlling it successfully and too strengthen it also.
Then experiment using it whilst masterbating. Don’t go for trying to hold off cumming by flexing it straight away. You will most likely fail. Instead make yourself hard and then whilst still rubbing, squeeze the tailbone muscle and see if you can make yourself lose feeling in your dick and start going soft even though you are still rubbing. If you do it correctly, you will succeed and then you should after a few sessions start taking yourself closer to orgasm and then flex and make yourself limp by squeezing it again.
You have now mastered how to use it and you can now proceed to taking yourself very close to orgasm and then flex it for just long enough to shut feeling off from your dick and lose the need to cum but still stay very hard by not squeezing for too long. You would have been rubbing your dick all the time but you won’t have cum and you will be able to go on and on so long as you squeeze the tail bone muscle when needed.
I don’t even bother waiting until I need to cum before I squeeze it. I just do it hear and there and then build up my excitment again and keep doing that.
Explore for yourself and you shouldn’t have any problems.