how would i cite this in mla format?
Citing a book's reference in MLA format is pretty simple, but it is dependent on which publication of the novel that you have. (Your publication might be different than mine, so I can't just give you the answer, but I can give you an example format that you will have to adapt to your own book.)
Shelley, Mary. Frankenstein. Publisher's name. City, State, Country
of publisher. Date of publication.
Now what I've done for you above is made the citation in hanging-indent form. That means that on your Works Cited (or References, Bibliography, or Resources) page, you would indent the second wrapped line of the citation. This would also go in alphabetical order according to whether or not you have other sources that you are citing. Also remember to follow the punctuation marks that I have shown you. Use periods and commas correctly and in the correct order.