Why did David compose this Mizmor?
Radak #1: He said it about himself, when he went from Tzarah to respite.
Radak #2: He said it about Yisrael, for them to say when they will leave Galus.
Malbim: It discusses what happened to him from when he tended flocks in the Midbar until he rose to kingship. His first years were best; he was isolated with his Maker. After rising to kingship, he always calls himself poor, for it separated him from clinging to Hashem! Hashem arranged that he sing for Sha'ul, kill Galyus, and Sha'ul try to kill him, and ultimately David would tend His nation 1 .
Malbim: He was like a son who will inherit kingship, but preferred to be separated in a hut in the Midbar. His father's servant burned the hut, and induced him to live in a nicer dwelling closer to the capitol, and again
What is the significance of "Mizmor l'David"?
Rashi (from Pesachim 117a): When it says "Mizmor l'David", he sang, and then Shechinah (Ru'ach ha'Kodesh) rested on him. L'David Mizmor" teaches that the Shechinah rested on him, and then he sang.
Where is Hashem shepherding David?
Rashi: In this great Midbar that I go in.
