Chapter 1 of The Catcher in the Rye introduces the narrator and starts his recollections of the "madman stuff" that happened to him the previous Christmas starting with the night of the big game at Pencey.
Holden introduces his brother D.B., who regularly visits him at the institution he is narrating from.
Holden also introduces Pencey Prep School and its tendency to be superficial, after experiencing the school firsthand.
Holden mentions his trip to New York with Pencey's fencing team, which he is manager of.
Salinger establishes Holden's style of narration, which is somewhat casual and reflecting of teenage colloquial speech of the time (i.e. 1920s), but the reader is not given any clear description as to whom Holden is talking to or where he is. Holden however hints that in the present time, he is in a medical institution near Hollywood to "take it easy", mentioning how he "practically got t.b. and came out here for all these goddam checkups and stuff". He would further hint his location during the final chapter.
During the narrator's introduction, he mentions "David Copperfield kind of crap". Younger reader usually mistake this reference to the illusionist David Copperfield. Holden is instead referring to the Charles Dickens novel, whose first chapter is about the titular character describing his birth. Interestingly, this chapter of David Copperfield mentions a "caul" or the membrane covering a fetus' head. Some interpretations argue that this reference to David Copperfield suggests a relationship to Holden's last name and being the "catcher in the rye", further explained in Chapter 22.
Holden mentions that he was the manager of Pencey's fencing team as he recalls their trip to New York for a match against McBurney School, an actual preparatory school in Manhattan which closed down during the 1980s. J.D. Salinger attended McBurney where he also managed the fencing team.