Hamelette says "If you've never participated in one of my read-alongs and are curious about how they work, basically I will write a post for each individual chapter. Each post will contain my own thoughts on the chapter, some favorite lines, and a discussion question or two that I think people might want to ponder. All participants are then invited to discuss the chapter in the comments, both with me and with each other. You don't have to stick to the questions I ask!"
Sounds easy enough. Gatsby is one of my favorites. It should be fun to discuss the book in a group.