Watch the Sweet D online guitar lesson by Corey Congilio from Acoustic Rhythm Guitar Playbook
This progression in the key of D is a classic. I love the cascading sound of a D to Dmaj7 to D7 chord change. The most important thing to notice in this example is the one note that is moving through the changes. Listen for that, as it will show you if you're playing it properly. I'll explain it deeper in the video.