Am I using the prostate stimulator wrong?

So, I have been very intrigued by the idea of having an orgasm via prostate stimulation. So, I bought the Aneros Helix because I read everywhere online that it is great for beginners.
When I insert it, i don’t really feel anything. I have done what the guide says “tighten and release your muscles to move the stimulator in a back and forth motion.” And it does move in a back and forth motion, but i only feel the sensation when I tighten the muscles. I BARELY feel that “peeing” sensation that I’ve read about online. And as soon as i release the muscles the feeling goes away, & is difficult to get back.
I have tried using my hand to move the toy in & out as I tighten my muscles and this feels amazing, but as soon as I release the muscles, the feeling goes away quickly. I can’t keep my muscles tight forever. How will I ever reach an orgasm by using the Aneros Helix?