Most articles walk you through the basic steps of getting your iron sights zeroed, but they lack an explanation of why you're doing the steps you're doing. Let's change that.
Iron sights are not magical talisman that turn you into a rifleman. They are a tool for executing marksmanship, not part of the "fundamentals." Don't get wrapped up.
RIBZ stands for Revised Improved Battlesight Zero. It's a method of adjusting standard military carry handle sights to allow a wider range of zeroes. This leverages one of the primary benefits of the adjustable sights over fixed sights. This guide shows you how to implement RIBZ.