If you need help with MLA format and you can't figure out how to use your printed MLA guide, you can use the very helpful OWL site from Purdue's Writing Center:
Too often the Works Cited page does not match up with the works used in the essay, and this is frustrating for the teacher grading the essay and disappointing for the student when the essay comes back with huge points taken off.
Use the MLA guide to format your citations. RefWorks and OneNote and online formatting things which have you enter the ISBN number and then generate your citation for you are too often wrong. Best to do it yourself. If you are absolutely helpless at this, consider doing it yourself and then double checking using WorldCat's formatting (make sure you set it to MLA), which I have often found to be correctly done.
EVEN IF YOU ARE USING ONLY ONE OR TWO TEXTS (in, say, a critical analysis essay which is a close reading of a single text) YOU ALWAYS CITE ANY AND EVERYTHING YOU QUOTED IN THE ESSAY.
If all you have is a single source, and there is plenty of room at the end of the last page of your essay for it, you do not have to start a whole new page for just one citation, you can just hit Enter a few times to make some space and then tack the one citation on at the end.