Plavini yoga Belly inflation

I've heard about the plavini yoga inflation and would really like to learn how to do it, but I can't seem to get it right when I try, I can puff my cheeks out and push the air down into my stomach, but I don't think that's how smooth it should be, could the people who do this way please provide a description of how they do it?

Thanks.

Dregoknight.