What are the chapter titles in Stargirl?
"Porcupine Necktie" is the phrase that we first see in this story. It looks like a chapter title: centered, bold, in all caps, printed halfway down the page with just the blank space above it.
The phrase "porcupine necktie" is a reference to the funny accessory that the narrator is given by his uncle, as well as the second silly item given to him as an anonymous gift. (We'll figure out later that it was Stargirl who sent the second porcupine necktie!)
However, after this brief section, there's a new chapter labeled "1." So we can understand that the porcupine necktie section was actually the prologue, or the little bit that comes before the main story, telling us something that happens that will probably become important later.
Chapters 1 through 33 are simply labeled with those numbers. They don't actually have titles, like some book chapters do.
Finally, the book closes with a section labeled "More Than Stars." Again, it's in all capital letters, bold and everything. This time, since we already noticed that the prologue had the same kind of label, we can understand more quickly that "More Than Stars" is the epilogue: the final, extra bit to the story that tells a little bit more about how things ended up. "More than stars" is a reference to the bigger impact that Stargirl made on the narrator, which he describes here, looking back on the whole story as an adult. And he also receives another anonymous porcupine necktie gift!