The Question and Answer section for To Build a Fire is a great resource to ask questions, find answers, and discuss the novel.
I can't go through each point with you but I can make a general statement. The old Timer told the man never to travel in cold like he was experiencing and, in particular, never to travel alone. The man's judgment was clouded by his own arrogance...
What thoughts in particular are you referring to?
The men realizes that his only hope for survival is to be able to build a fire.