The Ghost of Christmas Past visits Scrooge, because it uses Scrooge's very own painful memories against him, as a kind of a way to show him what poor people suffered in the time of the story. It wants him to become a good person.
The first ghost to visit Scrooge was that of his business partner, Jacob Marley. Later Scrooge was visited by the Ghost of Christmas Past, Christmas Present and Christmas Yet to Come
When Scrooge touched the robe of the ghost, he felt a chill run through him and it caused the ghost's form to dwindle down to the size of a child. This hinted at the spirit's fragile nature and the impact of Scrooge's actions on the ghost's existence.
The Ghost of Christmas past brings Scrooge to a party at Scrooge's first employer, Mr Fezziwig's.
At 1 am
Marley
The first ghost to appear before Ebenezer Scrooge in The Muppet Christmas Carol is the Ghost of Jacob Marley, Scrooge's former business partner. He warns Scrooge about the consequences of his selfish and greedy ways.
The very first ghost is Jacob Marley
scrooge's partner Marley visited him first
Technically, the first ghost to visit Scrooge was the Ghost of Marley (Jacob Marley, Scrooge's former business partner who died 7 Christmas Eve's earlier).
He takes Scrooge to his old boarding school.
Scrooge was never a ghost in the story
The first ghost (having been foretold by Marley) was to take Scrooge back to his previous Christmases and allow Scrooge to see what it was like for him then and how this changed him