Heart of darkness

This book was super difficult for me to read. It was frustrating because it was so short yet it took me so long to read. I had to re-read a lot and I had to keep stopping because it was too hard to focus on for long periods of time.  The actual book was confusing to me and i am not sure i really understood any of it. I do not understand why everyone was so obsessed with Mr. Kurtz. :I also do not understand the whole concept. Are there a bunch of men just sailing around an the narrator is just telling a story?