[galaxy-user] CloudMan - Galaxy - How does sharing work?

I was wondering how the sharestring feature works? Enis mention it a little bit here: http://biostar.stackexchange.com/questions/15467/galaxy-cloudman-best-way-to... So as I understand it, I do my customizations and persist them, and then I get a sharestring so others can load my customizations. How does this work behind the scenes? Also where are my customizations stored? Am I charged by Amazon for storing them? How do others have permissions to pull them from my Amazon account? (I'm new to all of this, sorry if my questions are obvious) -Greg