This topic involves one of my favorite passages in the short story. One contrast is between the narrator's fantasy of herself--the mother that Dee would respect and love; the other as the narrator sees herself. The first image involves the mother on the Johnny Carson show being introduced to an adoring audience and embraced by an equally adoring Dee: "a hundred pounds lighter, my skin like an uncooked barley pancake. My hair glistens in the hot bright lights." The other image is that of the narrator in real life:
large, big boned woman with rough, man-working hands . . .I can kill a hog as mercilessly as a man. My fat keeps me hot in zero weather . . .I can eat pork liver cooked over the open fire minutes after it comes steaming from the hog. One winter I knocked a bull calf straight in the brain between the eyes with a sledge hammer and had the meat hung up to chill before nightfall.
There's much to admire in a woman like that!
In addition to the contrasting details regarding character descriptions of Maggie and Dee, the ridiculousness of the name that Dee has chosen to be called and her attire now in contrast to what she used to prefer helps the reader to assess false sense of value that Dee now possesses.
For instance, the mother narrates that Dee used to want nice things such as a yellow organdy dress, black pumps to go with a green suit she had made. Now, as Wasuzo Teano she wears a long dress that is so loud that it hurts her mother's eyes. She also wears huge hoop earrings and "Bracelets dangling and making noises when she moves her arm up to shake the folds of the dress out of her armpits."
You would do well to develop your analysis of how the characters of Maggie and Dee are described. They act as foils in the short story, which means Walker deliberately places them together to heighten the contrast between them. Consider how Mama describes both of her daughters - Maggie is described as a lame animal whereas Dee is described as incredibly confident. There are certainly lots of references at the beginning of the story that you can use to answer this question. Once you have identified these references you can expand on them by seeing how their actions in the later part of the story reflect their character as has already been established.
Concrete details are also general descriptive details that help create a strong sense of setting, place, and time -- colors, temperatures, descriptions of rooms, the quilt's looks, etc. When we ask students to use "concrete" detail, we're asking them to step back from abstract narration ("telling") and to set the scene ("show") for the reader.
Concrete details are those that are stated openly which we don't have to read between the lines to get. We know Maggie is quiet because both Dee and Momma say so. We know she is scarred from the fire. We know Dee is beautiful--both Maggie and Momma make statements to the effect. We know Dee is confident--her bright clothing, her posture. The description of her slender and well-formed leg coming out of the car helps develop this.
Keep looking for directly stated comments and observations that help you "picture" the character and get to know him/her better.