Watch the E Major Diatonic Triads online guitar lesson by Joe Dalton from Fretboard Epiphanies
Here are the triads in E major. Notice how they follow the formula. (major, minor, minor, major, major, minor, and diminished) The root of each triad is on top. The highest note will be perceived as the melody. When the 3rd is the lowest note, it is said that the triad is in 1st inversion. Make certain to use the proper right hand fingers as you learn and drill these patterns.