Obviously, depending on which edition of this excellent novel you have the page number will vary, but I assume you are talking about the conversation that Jem and Scout have with Dill when Jem repeats the local gossip and horror stories about Boo Radley to Dill to try and terrify him. This is located towards the end of the first chapter and the quote you are after is as follows:
Jem gave a reasonable description of Boo: Boo was about six-and-a-half feet tall, judging from his tracks; he dined on raw squirrels and any cats he could catch, that's why his hands were bloodstained--if you ate an animal raw, you could never wash the blood off. There was a long jagged scar that ran across his face; what teeth he had were yellow and rotten; his eyes popped, and he drooled most of the time.
Note the way that these legends and rumours feature massive elements of exaggeration and classic elements of childish horror stories such as the consuming of raw squirrels. You might wish to consider the description of Boo Radley and the stereotypical elements of his appearance. Crucial to the description of Boo Radley is the way that the children's attitude towards him changes during the course of the novel and the way that they treat him as more of a human as they themselves grow up and mature.
Towards the end of Chapter 1, Jem repeats the local legends and rumors surrounding their reclusive neighbor Boo Radley. Jem gets most of his information from Miss Stephanie Crawford, and repeats one of the rumors she told him about Boo Radley. Jem tells Dill that at night, Boo Radley roams throughout the neighborhood and peeks into people's windows. Miss Stephanie even swears that she saw Boo staring at her through her window in the middle of the night. Jem then tells Dill that he heard Boo scratching on their back door one night, but Boo managed to sneak away as soon as Atticus arrived. Jem then gives Dill an elaborate, imaginative description of Boo Radley. As was mentioned in the previous post, Jem describes Boo Radley as a terrifying, grotesque creature who eats raw animals and is covered in blood.