As i sat waiting for the school bus i read a few chapters from a novel.
what is the correct way to punctuate the underlined part of the sentence

I don’t see anything underlined, but I can answer as to how this sentence should be punctuated. The sentence should be punctuated as follows: As I sat waiting for the school bus, I read a few chapters from a novel. The comma is needed after the phrase “As I sat waiting for the school bus” because that’s a conjunction phrase because it begins with the word “as.”