These are a few general guides on university websites, but remember to speak to your professor if you need specifics.
The Reference Shelf lists many sources for overviews of authors, works, and literary terms. The following are a few entries are specific to your project.
In addition to simple searches for the author or text -- like Interesting Narrative of the Life of Olaudah Equiano -- you can try adding terms like (handbook* or companion* or guide) to find overviews or crit* to find secondary sources. Farm the official subject headings for more terms and use parentheses and "or" to create searches like:
Remember to always check the official subject headings for more ideas and a sense of the hierarchy of topics.
You may not always find a perfect article with an exact title reflecting your topic. Rather than find an article called "Nationalism in The Narrative of the Life of Frederick Douglass", you may find an article that says something interesting about nationalism and Douglass, and connect it to The Narrative yourself.
The following links show how to construct a few searches in the MLA Bibliography using advanced limiters; however, you must choose the articles most relevant to your thesis, and use those articles to brainstorm more search terms for finding additional articles.
The following article databases are the best places to start for research in literature and drama: