Watch the Return to B online guitar lesson by Brad Carlton from Chord Studies: Slash Chords Vol. 1
In this example we are in the key of E and we are using a I-V/I-vi-V progression. Start with a typical E chord then move up to the B/E, which you'll notice utilizes the same B shape we will using in measure four. From C♯m7, your second finger is a guide and you move up to the B. Take note of how the B chord is essentially your A form with your finger acting as capo at the second fret.