Kristina, I have no wish to deter you from writing, but I find myself asking if English is your mother language.
The first thing that strikes me about all of your work, including the unfinished pieces is that your spelling is absolutely dreadful and your grammar isn't much better. This is why I ask if perhaps you are not English. However whether you are or not you should remember one thing. Spellcheck and in your case Grammarcheck are your friends. It's not enough to have what you think is a 'cool' idea, jot down a few practically incomprehensible sentences and then ask your readers for their approval. Let's go through your concept:
1. Saruman would have no need of another archer simply to 'take out' (this is modern terminology which wouldn't have been in use in Middle-earth) the man, elf and dwarf. Saruman had a monstrous army of tens of thousands of orcs and Uruk-Hai. After Helm's Deep and Treebeard's attack on Iseguard his power was virtually shattered. Previous to those events he would have had no need for one young girl archer, no matter how good she was.
2. Gwen is in danger of being a Mary Sue, albeit for the side of the enemy. She has 'speshul' abilities, her heart is still kind and good despite being aggressive and not having a care in the world. She cannot be both good and kind and a potential tool for evil.
3. There is nothing wrong with exploring the concept of a female ranger at the time of the Third Age, except that women would not have been thought of as warriors in that time. Eowyn was an exception as a Shieldmaiden of Rohan and even she came in for a hard time from the men. This is why she ended up defying Theoden and her brother and riding to the Battle of the Pelennor Fields. Women in Middle-earth had their place and it wasn't on a battlefield, unless they were robbing corpses or searching for injured loved ones.
If you must explore the concept then the notion of a girl joining the Rangers because she felt as if she had no future would be far more interesting if you got her disguising herself as a boy, then joining the Rangers and learning the craft of archery and fighting there. The Rangers only find out that she's female when the battle is over.
This is just an idea that someone could enlarge and write. I took your concept and altered it to fit the genre and Tolkien's original story, which is of course something all fanfic writer should be respectful of. This is someone else's hard work we are all playing around with here!
At any rate, you can do one of a few things. You could ask other writers in the community for assistance in beta reading your work, you could, and should most definitely read the books. Do not just rely on your perception of the movie. You could ask someone like me for assistance. I write fanfics, but I also have a novel due to be published at the end of the year.
Another problem you seem to have is careless writing. Capital letters should be used at the beginning of sentences, for proper nouns (Names, place names etc) and the word 'I' e.g. I will, NOT i will.
Another thing to remember is that demanding reader's opinion of an idea for a fanfic before writing the piece is a bit silly. Readers don't know what they like until they've read it and a few sentences in summary form do not a fic make. Write the first chapter, get it beta-ed, publish it and wait for reviews, don't demand them before you write more.
Author's Response: excuse me but this is my fan fiction since when i asked the featherserpent to edit and tell me what to write and what is wrong! no i didnt! so fuck you! and yes im english but i was in a freakin rush when wrote it , b/c usually i write very long and take days to perfect every thing but i didnt have time b/c ppl kept rushing me! and yes sarumon in MY fan fic wants her to be their assassin , thats the point of the word FAN FICTION! your own every thing you want to happen not other people! so leave your pathetic comments to your self! i dont give a shit! so yeah whatever...
Author's Response: also i have many reasons for sarumon wanting gwen as there assassin she hold POWER key word i just didnt get there yet , so just leave me alone , i know you can find somthing better to do then leaving long reviews about shit i DONT care about . I dont appreciate your review , like the saying if you cant say somthing nice then dont say anything at all , and now a new one if you cant review a story nicely and look at the positive then dont fucking write at all! okay ? copiesh? good now bye!
Violet, for heaven's sake honey, grow up a little. I merely told you to use spell and grammar check and perhaps get a beta reader. That's not negativity it's both common sense and constructive. The decision to erase your story was your choice and yours entirely. Now please stop using the review system for my story in order to highlight your own difficulties. You're not damaging me or my story, but merely making yourself look silly. Jeez, I can't believe I am using my own story to reply to your idiocy!