Apart from learning digital marketing through eLearning or classroom programs, you must purchase a good book for self-study. Sometimes the topics are not explained systematically in the digital marketing courses, so books can be beneficial to strengthen your knowledge. You can learn digital marketing from the faculty of IIM Bangalore, Prof Seema Gupta. Check out the link below to purchase the book designed for beginners.
DIGITAL MARKETING by prof Seema Gupta from McGraw Hill.