I am sorry that the lecture felt overwhelming; I should have explained it more simply. However, this is not originally an easy course. Please feel free to ask questions whenever you are curious. Since you have only completed about 17% so far, you need to finish 100% of the course and listen to it repeatedly to truly make the knowledge your own. In fact, it is perfectly natural to feel overwhelmed right now. Even professionals with 10 or 20 years of experience find this content difficult. You have been leaving many questions, and I encourage you to keep doing so. Even minor questions are fine. Those questions accumulate to become your skills. (In fact, I can see a lot of evidence of your hard work in your questions.) Please don't give up, and I hope you complete 100% of the course until the end. You can do it!