Submarine pitching release?

I am new to submarine pitching (and baseball in general.) So I have a lot to work on, especially with technique/form. I’ve been getting a little bit better everyday, but what has been troubling me is where/when do you release the ball when you throw a submarine? I usually mess up on my release and I end up throwing the ball crazily and really inaccurate (I’m pretty sure they would be wild pitches in a real-game situation, haha.) Also, would the release be underhand or a low sidearm? Thanks!

Here’s some video you can look at that might help you:

Hope this helps. The animated motion of Josh Papelbon helps a lot.