The hardest part of the Dbmaj7 is the barre chord. Place your index finger over the entire first fret and make sure all the strings sound when you press down. You may have to make small adjustments in your finger position until you hear no dead strings. Once you have the barre in place use your ring finger to play the third fret of the A string. That stretch between the ring and index may be a little rough at first, but it will get much better with practice.