I need more... in order to be hooked to this story. I have a feeling I will like it, but I have learned from experience that FIRST CHAPTER MUST BE LONG!!! Try to make them at least 1500 words.
I will beta you if you like, I don't know if you making spelling and grammar mistakes a lot, the piece is fairly small to judge.
Please update or contact me, I'm thirteen as well. I am anxious to read more and see how this unfolds, maybe try editing it so others will think so too. This is not meant to be an insult, just trying to help. :) Good luck!
Your character has all the makings of turning into a Mary-Sue. The exotic name is a clue, for one. And the idea of her changing things in Middle-Earth as well. You haven't written enough yet to judge, but I'd be careful.
I'm not sure about your suggestion in the summary that Tolkien hadn't actually written all his books, that he had taken writings from ME characters. Your way of bringing your character to ME sounds very unique, so I will say that's impressed me, but it seems rather disrespectful to suggest even in a story that a genius like Tolkien wasn't really responsible for his masterpieces. I'm sure you're not intending it that way, but it still seems a little rude. It is also something that is bound to annoy all the hardcore book fans on the site.
I think you should probably have tried to make this first chapter longer. The first chapter of a story is very important for keeping readers interested, and a short prologue like this isn't going to catch many people. At least, you should have added a bit more detail.
Your writing style seems ok so far (it's hard to tell at this stage) but I would watch your spelling. For instance, 'booktrilogy' (incidentally, LotR isn't a trilogy. It's six separate books). 'Doughter' should be 'daughter'. 'It's writer' should just say 'its writer'. It's with the apostrophe means 'it is'.
I'm sorry if this review sounds very critical, I'm only trying to be helpful. This could turn out to be quite a good story. I'll keep an eye out for the next update!