I assume you are asking about the day that the Tom Robinson trial begins in Chapter 16 of To Kill a Mockingbird. Before Atticus left the house after breakfast, he warned Jem and Scout to stay away from downtown, and Aunt Alexandra told them to "stay in the yard today." They watched a "steady stream" of people pass by their house on the way to the courthouse.
As the county went by us, Jem gave Dill the histories and general attitudes of the more prominent figures...
A group of staunch Christians quoted the scriptures to Miss Maudie, objecting to her "vanity" for the colorful flowers she displayed. Maudie then questioned Miss Stephanie about her plans for the day, knowing that she could not stay away from the trial. Naturally, the children could not restrain their curiosity:
We held off until noon... After dinner, we stopped by for Dill and went to town.
Picnickers were enjoying chicken and pork chops on the courthouse square. In the corner of the square, the Negroes ate their sardines and crackers; Dolphus Raymond was with them, and Jem related his knowledge of the man and his "mixed" children. They observed members of the Idlers' Club discussing the upcoming trial and, near the courthouse entrance, the children got some news of their own. They discovered for the first time that Atticus had been appointed by the court to defend Tom, and the men they overheard were concerned since
"... Atticus aims to defend him. That's what I don't like about it."