Lizzie, if you have a penchant for writing and are willing to improve upon your English composition consider the avenues of journalism or creative writing, such as magazine articles, short stories, and even political submissions. If not that, you might begin now by preparing yourself as a...
To prevent plagiarism and risk of a copyright law suit by the publisher and the author you should write using your own characters. Yes, the temptation is there to combine your work with that of Meyer's, but if you try to publish your manuscript you would risk a law suit.