The note D is written on the fourth line of the staff.
The following example alternates between the notes D and C. The only difference in fingering here is that the thumb is not used for the D note.
Now try this example which combines the note D with the other notes you have learned. Breath marks are only shown every four bars here, but breathe every two bars if necessary. As your playing develops you won’t need to breathe as often as in the beginning stages.
Because you have to think about moving your thumb as well as the other fingers, it may take some time to become comfortable changing between D and all the other notes. Here are some more songs to give you extra practice at moving between all the notes you have learned.
This one is in ^ time. There are no breath marks written here and no rests until the final bar, which means you will have to find your own places to breathe. A good place to breathe is at the end of any of the dotted half notes, just before you play the following note.