Lennie was wondering what they are gonna eat at the fire. George said he has 3 cans of beans but Lennie said he wanted ketchup with his beans, George said we have no ketchup. This shows that they don't have everything, they have to work for most of there things. The message is you don't always get what you want.
George said, "well he seen this girl in a red dress." Everyone knows that the color red means evil which might lead to blood and Curley's wife was wearing red. This Foreshadow lead to someone or let's just say Lennie was tempted to kill someone or something. The message is when tempted just to say no.
Lennie is now petting a dog alone in a barn and he ends up petting the dog a little to long and a little to hard and let's just say the dog ends up passing away. This pretty much shows that Lennie is not the type of guy to mess with, he's very aggressive and strong. The message to this chapter is don't be aggressive towards little things.
George and Lennie go to a river. Lennie wants George to tell him the dream farm story , while George tells him the story, George tells Lennie to look across the river and imagine a farm across the river while Lennie is looking George pulls out a gun and pulls the trigger. George pulls the trigger because he could not deal with Lennie anymore. The message from this chapter is Look out for yourself before you look out for others.