Q: How did the Psalter come about?

"David arranged for the composition of the Psalter because he had received a covenant promise from God that his heirs would serve as the leaders of God's people forever. (2 Samuel 7) The Psalter was prepared in David's temple arrangements for use in the Lord's worship."

(From '150 Questions about the Psalter' by Bradley Johnston;http://www.crownandcovenant.com/product_p/ds199.htm)