Watch the Bass Cadet online guitar lesson by Brad Carlton from Chord Studies: i to V7 Vamps Vol. 1
Your first chord is just a standard Dm barre chord form with a fifth string root, except we are leaving the first string open. For your transition you move down a half step to the A7add♯5, then bring the C♯ into the bass for the last chord. Notice the bassline moving throughout the progression.