Watch the Chord Extensions Pt. 2 online guitar lesson by Brad Carlton from Guitar Lab: The Imaj7 IVm6 Progression
In this lesson, I'll demonstrate adding the 6 to each of the chords. There are two ways to locate the 6(13): It will always be a whole step higher than the 5 and a whole step lower than the 7. Knowing this enables you to take any chord voicing and modify it to include the 6(13).