You log in, go to "Course Materials" over on the right. And select which semester or "term" you want to start. Ideally, CCNA 1, start from there, study each chapter, and then when you feel very confident, start CCNA 2. Ideally, CCNA 1 is about a semester long or about... 21 weeks... as well as CCNA 2, 3, 4.