I can’t find any thing for the first 6 chapters, so is there any lecture available for first 6 chpters or they r for self study? Is it okay to start from chapter 7 or should i do first chpters before i start chpter7?
The first few chapter are more background reading, without any big calculations. You should certainly read them, but that is why there are no lectures on them.
(In future you must ask in the Ask the Tutor Forum if you want me to answer. This forum is for students to help each other.)