Doing this will involve defining at least briefly what a "literary" text is. You can, of course, come up with a definition of your own or employ the definitions of others — dictionaries, quotations, etc, etc. 

Here’s one way of writing the paper (feel free to develop alternative approaches, of course): 

Introduction/Thesis (First paragraph — about 1/2 a page): 

Define "literature" and introduce the two texts you will be discussing – either "I am Legend" and at least one other more "literary" text. You will also need a thesis, one that indicates your position on what makes a text truly literary and whether you think either "I am Legend" or "Jaws" qualifies as such. 

Middle Section of Paper: (3-4 pages) 

This section could have two parts — a brief discussion of a "literary" text and a longer one of either "I am Legend". It is okay to talk about the literary text in general terms — you certainly don’t need to reread it, though you might look at the Wikipedia article on it and do some additional research: you do need to go into some detail about either "I am Legend", however: quote the text in support of your argument. You also need to cite any outside sources you use, including Wikipedia, Sparknotes, and the like. 

Conclusion: (about 1/2 a page) 

Conclusions should go beyond merely summarizing what has been argued previously in the paper. The best thing to do is revisit your thesis and discuss its implications. For example, if you argued that "I am Legend" was really not all that different from "The Old Man and the Sea" or "Moby-Dick" and that, therefore, the line between literary/non literary is not always easy to see, then in your conclusion you might discuss how students should be assigned a broader range of texts in literature classes, not just the ones that are not usually taught.