Start your research with encyclopaedias to get a broad overview of an subject area, concept or field as they have article length entries, suggestions for further reading and other helpful background information.
Other encyclopaedias can be found by using 'encyclopedia' and 'gender' with terms such as 'sexuality', 'media' etc. in Library Search.
Edited books are also good sources of information for undergraduate subjects as they have essays / chapters written by different experts on a topic, and can help you find more recent and in depth material than encyclopaedias.
Dig deeper in databases to find more types of information you will need in Gender, Sexuality and Diversity Studies research - including media, policy, literature, and histories.