You can go to the local self-study examination office (examination center, education examination institute, education bureau and other institutions) to sign up for the self-study examination.
The process of self-taught examination is: self-taught examination registration-booking or purchasing teaching materials (books)-receiving books, self-study-taking exams on schedule-completing all courses-applying for graduation-obtaining college and undergraduate degrees.
Please go to the local (provincial) self-taught official website for information about teaching materials, which is published above. Pay attention to the difference between these websites, and be sure to find this official website. According to these published textbook information, you can also buy textbooks online.