Please help explain contractions to me.

I've read numerous tutorials and FAQ's here and on the aneros forum and for some reason I'm just not really grasping how exactly to do contractions or if I am doing them right.

I've watched a ton of videos of other guys using the aneros and I can clearly see the toy moving freely inside of them….I never feel the toy move inside at all.

Any tips or links to helpful videos/articles would be very much appreciated.

Thanks.