To play a D7 chord on this type of keyboard, press the D key shown on the diagram with the thumb of your left hand, together with the white key to its left using your second finger.
To play a D7 chord on this type of keyboard, press the D key shown on the diagram with the third finger of your left hand, together with the two white keys to its right, using your second finger and thumb.
The fingered D7 chord is the same for all types of keyboards. To play the D7 fingered chord, use the first, second and fifth fingers of your left hand.
When changing between the F and D7 fingered chords, keep your second finger on the C key. When changing between the D7 and G fingered chords, keep your thumb on the D key.
When changing between the D7 and C fingered chords, keep your second finger on the C key.