What did Scrooge do after his visitor left?
More details, please. Which visitor are you asking about? In addition to the four spirits (Marley and the three ghosts of Christmas) who come to Scrooge, he is also visited by his nephew and by two men seeking a donation for charity. Your question cannot be answered without more details.
After the visitor left, he turns around and start walking upstairs. We learned that he is very conservative with his money. He makes everything himself even though he is rich. He goes in his room and he mentioned specifically he never locks his doors. Strangely he mentioned he "Double Locked" it today. Soon Marley's ghost would appear out of no where.