How do Oscar award winners get picked?

i know only some rules of the award selection.... There are certain srules for this... 1-film must open in the previous calendar year, from midnight at the start of January 1 to midnight at the end of December 31. 2-a film must be "feature-length", defined as a minimum of 40 minutes 3-it must exist either on a 35 mm or 70 mm film print .. From this film categories Judges select for each item...