The key to writing a paragraph like this is to determine which conflict you would like to examine. There are several in the story, but the most prominent is the conflict Scrooge faces within himself. He is not a very good person and the story is about him struggling to see that and then change into a better person. It takes a lot of work on the parts of four spirits (Marley included) to get Scrooge to change!
If we use this conflict as an example, you might want to find some quotes that would support this conflict. If you are only writing a paragraph, you probably only need two-three examples, but it might be a good idea to find those in advance so you know who you will tie all of them together. Here is one quote that exemplifies his inner conflict. Here, he is talking to the Ghost of Christmas Future and asking if he were to change his behavior if his own future would change:
“Before I draw nearer to that stone to which you point,” said Scrooge, “answer me one question. Are these the shadows of the things that Will be, or are they shadows of things that May be, only?”
Still the Ghost pointed downward to the grave by which it stood.
“Men’s courses will foreshadow certain ends, to which, if persevered in, they must lead,” said Scrooge. “But if the courses be departed from, the ends will change. Say it is thus with what you show me" (Stave Four)!
While this quote is fairly long for a paragraph, you could easily choose one portion of it to talk about. Consider grouping it with one or two other examples of this conflict and then writing a paragraph that focuses on that conflict in the story.