That totally depends which institution you want to petition!? Like, how do I officially petition my neighbourhood council? Or how do I petition my boy scout association for something?

There are many cases where it’s just “I and those 50 people want something from a very local instance of something”.

Hell, it could be, that I want to ask my local grocer to list a specific sort of pepper and show them, that he would have more customers than just me, so it’s worth his while.