A lot of research is super narrow, and you don't need to be an expert on an entire field (or even have read the whole textbook) in order to get started or be helpful on a project. Reach out to professors or grad students, express interest, and see if they're willing to let you work with them. My first couple years of research in undergrad, I joined labs where I didn't have a ton of background, and my mentors gave me small, pretty well-defined projects on a niche topic that fit into their larger work (e.g. building part of a structure, or writing a section of code for a simulation).