How to contract muscles

You can do both/either. There's another kind of contraction that seems to push the aneros closer to your belly, but it's really obscure to get the hang of. Just experiment with what feels good.
Sometimes the best thing to do is not do any contractions at all. Just let the aneros sit there, and concentrate on the subtle sense of pressure.
You can't really contract pleasure into existence, at least not by itself. A common mistake when starting out, is to get too hung up on what the right movements are. Which is understandable, since it seems to be the only thing you can influence.
I think the way forward is to narrow your focus to the very smallest of sensations... what does the pressure inside feel like? What else is that area connected to? Does it feel even a little bit good? Those very slight sensations can grow, and sometimes they grow just by being noticed.
If you haven't done prostate stimulation before, it can be a very different set of rules, even to the point where it gets weird and doesn't even seem to make sense... sometimes it's more like meditation.
It's quite typical that people don't feel much at first, because it's hard to know what you're even looking for. I think the body learns things too, so mere practicing is just as important as any technique.

Posted by: @lowie0098

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Can anyone give me some tips/links/photos/videos?

I agree with everything @Clenchy said above and will add some further reading for you. Please see the Aneros WIKI> Getting Started> Contraction Exercises & Aneros WIKI> Advanced Skills> Exercises, then follow that with @BigGlansDC 's thread The Kegels do work! Especially with Aless! this was based on Kegel Exercises For Men. Then I recommend you read @Helghast 's thread A simple prostate orgasm tutorial. for a general discussion of the pelvic floor muscles, how to find & employ them toward prostate orgasm and the concept of "anchored tension". Once you have gotten more familiar with your pelvic floor muscles you may wish to read @CaveOfMystery 's thread Quick and Dirty Path to the Super-O. You may also be interested in the guided contraction exercises offered on the Mindgasm.net website..

Good Vibes to You!