Psalms simply means songs. The psalms were songs and prayers of David, Solomon, the sons of Asaph, sons of Korah, Moses. Psalms 90 was a prayer of the man of God Moses. It literally means David was a musician with an a gift of being able to write songs. He too could play instruments. This is shown when he would play his instrument before Saul for the evil spirit to leave Saul. Most of David's psalms are about how God delivered him from the hands of his enemies. Psalms 3, was written when God delivered him from the conspiracy of his son Absalom. Psalms 18 is similar to 2 Samuel 22 and it is basically how David was talking about God's wonderful protection upon his life.