The D major thirteenth chord is a 6-note chord consisting of the notes D, F#, A, C#, E and B.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Dmaj13.
Interactive piano diagram for the D major thirteenth chord
Chords that are a subset of Dmaj13. These contain less notes but all of them are included in Dmaj13.