I know it contains reference/stories/event that happened at the life time of the prophet and was compiled some 100 years after his death. 

**My question is how it is compiled? There are different books, different chapters. In some online references there is 4 digit reference to hadith, in other it is volume 1, book 5, number 248.**

My question is is there one compilation (order) of Sahih Bukhari? How is it compiled? How can I use it best?