I'm not sure the question is completely clear, however, I will answer it as best as I understand your question. First of all, generally speaking when you are writing a literary paper you are supposed to use MLA style citations, unless otherwise specified by a teacher. More information on MLA citations can be found at http://www.mla.org.
Second of all, I assume that when you say "12th grader" you are referring to a near high school graduate. In that case, you should be using references appropriate for college papers at this point in your academic career, particularly if you are college bound. There are many online libraries that provide very good literary criticism and academic articles suitable for use in advanced high school and college papers. JSTOR (http://www.jstor.org) is a popular and trusted source for litrary criticism and academic articles.
Questia is a similar oniline academic library (http://www.questia.com/). In addition, any online site for a public library (for example the New York Public Library might help guide your search for citations (http://www.nypl.org). Project Muse if another great resource, however it may be difficult to access if your school is not a subscriber.
If you are looking for more basic citations Cliffnotes, Sparknotes, provide very good overviews and basic analysis of most literature. The most important thing to keep in mind is that the most eligible citations are those from which you get your information.