Wow! That's a question!
Let's start with an understanding of Postmodernism. The term has been applied to much contemporary writing, particularly with reference to the use of experimental forms. Typically, works in this category are fragmented and deny the traditional order of things in the universe. In many cases, the "hero" is now an "antihero" since the author bucks against the normal and accepted.
"Meta-" is a prefix meaning "beyond, above, of a higher logical type." When it is added to form a new noun from the name of a dicipline or process, it designates a new but related discipline or process. Therefore, "metanarratives" would mean the process of analyzing and investigating the narrative form itself.
So, by deduction, we could conclude that the postmodernist would analyze and investigate narratives in such a way as to create the story with experimental story telling talent. I think of Quentin Tarantino's work--lots of flashback, flashforward, mental illness, and ingenious techniques of telling the story without using the typical chronological order. Nothing would be boring from a postmodernist's point of view...it would need to be different...maybe even difficult. A reader or audience member would need to be keen, plugged in, and completely in tune with what he/she was seeing/reading in order not catch all the minute details that give away the sequence of events.
Hope this helps!