Don't need a tutorial, really.

Those are for axes and hatchets. You just use them either along the edge, or from back to front, depending on your preferences. Neither method is going to be dangerous as long as you don't get in a hurry

You wouldn't use one of these to do proper sharpening, where you'd be maintaining the angle. It's just a field tool to keep things working well. I mean, you can do proper sharpening with one, it would just be slower and more annoying than a bench stone.

https://ruralfencing.com/products/pocket-size-axe-sharpening-stone

Looks like an axe stone. Can't recommend a good tutorial other than a scout who knows. But you might find some. The key is a grip that keeps all your fingers on the rim and away from the side you're using.