Once registered for classes, log on to Canvas and look at the syllabus for each of your classes. The syllabus will provide a list of the textbooks you will need. Remember to budget for the high cost of textbooks, and look for previously-used textbooks.
The CSU Bookstore, in the lower level of the Lory Student Center, has both new and used textbooks. Online resources like Chegg and Amazon have both new and used textbooks for purchase or rental, but make sure you will get them in time for the start of your class.