I know its a stupid question but where do they come from? How do these sites get a hold of them but I can't? Is it possible tos tart my own domain extension like www.yoursite.ast?

I undersand you ask how to register a new extension. You have to propose to ICANN, and submit a lot of doents, insurance, infrastructure and a lot of money. It's not very simple so...

man that was a good questioin and i didnt know the answer

Hmm that is a great question.... does anyone know of a site I can find an article or something on... I would love to find out.