Dickens is a master of creating dynamic, well-rounded characters that seem real because they have flaws as well as strengths, weaknesses as well as virture. Pip is one of those characters; we sympathize with him because he goes through things that we can relate to. We are introduced to him when he is a young boy who is constantly teased and mocked by unfriendly relatives--who can't relate to that? We've all been embarrassed and infuriated by family members at one point or another. We feel his terror at the Magwitch encounter, and his succeeding paranoia afterwards. We feel bad for him when his sister dies. Our hearts go out to him at his unrequited love for Estella; we've all had that feeling, and it's rough. Because Pip is so very real, and experiences common human foes, we can relate to him.
Sympathizing with Miss Havisham is a bit more difficult, because she is such an extreme character, living on the fringes of normal human experiences. Her tragedy in the past is the biggest tool for sympathy that Dickens uses. She was used, jilted, scammed and betrayed. That makes her more bizarre nature more relatable, and we sympathize with that plight. She is a victim; Dickens makes her so in order to win our emotions.
On the surface, Magwitch is a cruel, vicious criminal who terrorizes people for his own gain. But near the end of the book, we too can sympathize with him, for several reasons. The first reason is that he reformed himself and spent years making money for Pip's success. The second is that he is so pathetically alone and vulnerable; all he wants is for Pip to be happy, and we can't help but feel bad for him. Then, his sad death, and Pip's softened heart towards him helps us to sympathize even with the surly, rough Magwitch.
I hope that those thoughts helped; good luck!
Sorry the question was "How does Dickens create sympathy for his characters in Great Expectations , only: pip , magwich and miss havisham are needed , thanks