When a film is first released, you may be able to find film reviews in national or international newspapers. Type in the name of the film, and add a few other unique key words, such as the last name of the director or a major actor. Look for an option which narrows your search to "reviews" or "criticism."
Articles written about a particular film, film genres, directors, etc. can be found in many of our periodical databases. Think about what kind of film your are researching, and consider what academic discipline might have a special interest in examining and critiquing that film (sociology? history? art?) To find periodical databases, click on the "Finding Journal Articles" tab in this subject guide.
Use the Library Catalog to find books written about a film genre, film movement, a particular director or even a specific film. You may have more luck using the terms MOTION PICTURES instead of films. i.e. motion pictures and feminism. You may find a whole book about your topic, or a chapter within a book.