in the beginning of the book what point do you think the author is trying to get across?
Since your question is somewhat vague, it can be answered a few ways.
The first point that the author wants the reader to know is that the boys are stranded on an uninhabited island with no adult supervision. Coupled with this fact, the importance of the names of the boys is a point the author makes quite apparent, as we see with Piggy's name. Also, it must noted that many of the boys are younger than twelve.
A second possible point the author may be intimating at the beginning of the novel is that once children are not under the supervision of adults they can become wild, as witnessed when Ralph runs around the island nakedly in the very first pages of the novel.
A third possible point that the author may want you to know is that rules are essential for survival, as is noted after Ralph and Piggy find the conch, Ralph blows it to see who else is on the island; soon afterwards, a series of boys arrive and a meeting is held with the conch being the controlling element that gives anyone holding it the authority to speak, which is the first rule on the island. It is at this meeting that the boys elect a leader. The leader is Ralph.
A fourth possible point the author is making at the beginning of the novel is the foreshadowing of the evil in Jack, for he and his band of choir boys, who are wearing black choir gowns and caps, are described as a dark creature as they snake their way on the beach toward the direction from where Ralph blew the conch.
As you see anyone of these points can be used as an argument to answer your question.