The easiest way to do this kind of assignment is review each of the scenes where she is present. There are two in particular that give the best picture of her character: the first dinner party at Rosings and her visit to Elizabeth at the end of the novel.
Even before these scenes, her characterization is drawn through Mr. Collins' talking about her. He reveals that she is very wealthy and his patron, but we also learn that she is incredibly arrogant and controlling. Collins actually states in his failed proposal to Elizabeth that he is getting married because Lady Catherine told him he should. Wow!
Once Elizabeth actually meets her, we get the full picture and it is exactly as we expected. Lady Catherine is extremely proud, self-centered, and arrogant. She shows no qualms about questioning and passing judgement on nearly every aspect of Elizabeth's upbringing -- she looks down on her for not having a governess; she can't believe there are five daughters all "out" at the same time; she is critical of Elizabeth's musical talents. Elizabeth handles it all with an admirable aplomb, but we are left with a distinct dislike of Lady C. She seems to just believe she lives in a world were people of her class get to make all the rules and there is no thought that those beneath her socially can have any significant value.
This is made even more evident when she confronts Elizabeth at the end of the novel and tells her, point blank, that she is not allowed to marry Darcy. She really has no place to tell Elizabeth, much less Darcy, how to live their lives, but she also has no reservations in making her comments. Elizabeth will not give her the satisfaction of agreeing with her or even saying anything specific about how she feels about Darcy. Remember, at the this point Elizabeth has little idea of how Darcy feels about her and is not all that hopeful that they will end up together. She takes her stand merely on principle! That is why we cheer on Elizabeth and love that Lady Catherine fails and is put her place by the daring heroine of the novel.