Watch the Thumbs Down online guitar lesson by Brad Carlton from Chord Studies: CAGED Chords Vol. 3
The first chord of this progression is the is a D chord coming from the G form. Take note that your pinky should be muting the fifth string. Our A/C♯ is coming out of the D form, we're just putting the 3rd of the chord in the bass. For the Bm chord, try using your thumb to grab the B note on the first string. We wrap things up with a G chord coming out of the C form of the CAGED system.