What are some ways Harper Lee in To Kill a Mockingbird forces the reader into the characters' shoes?

Harper Lee provides details of the background of Maycomb and provides a young narrator who is learning about the way things work. 

The two main ways that Harper Lee allows us to walk in characters' shoes is to provide us with a young narrator, Scout, who is very personable, and to provide us with background details of Maycomb through Scout.  Because Scout is getting to know the ways of the world, since she is young, we learn what Maycomb is like along with her. 

Scout tells us all about Maycomb, providing us background on its founding and its history up to the time the book takes place. 

Maycomb was an old town, but it was a tired old town when I first knew it. In rainy weather the streets turned to red slop; grass grew on the sidewalks, the courthouse sagged in the square. (Ch. 1)

Because she is young, she has to learn empathy.  As she learns empathy, the reader appreciates the experiences of others along with her.  She explains things to us without filters, and we understand what life is like for Scout, Atticus, Mayella, Boo Radley, and Tom Robinson. 

An example of this is Scout’s reaction to Mayella during the trial.  Her father has been trying to get her to understand other people’s perspectives, and she looks at Mayella and is able to appreciate what she must be going through.  She puts herself in Mayella’s shoes. 

As Tom Robinson gave his testimony, it came to me that Mayella Ewell must have been the loneliest person in the world. She was even lonelier than Boo Radley, who had not been out of the house in twenty-five years. (Ch. 19) 

Scout’s understanding of Mayella is very important for the reader, because it is easy to demonize Mayella since she is the one who accuses Tom Robinson of rape.  The reader is going to feel sympathetic toward Tom Robinson, so Scout’s empathy is helpful.  

The comparison to Boo Radley is significant, because Boo Radley and Tom Robinson are two plot lines that weave through the story. Through Scout’s interaction with these plot lines, the reader comes to understand the people of Maycomb and appreciate the circumstances.  We pass through Atticus’s story, and Tom’s, and Boo’s, as we experience Scout’s.