This chapter begins the final Psalm written by David in the book. The final five Psalms (chapters 146-150) of the book that come next also focus on praising God.
We must always remember we don't praise Him for His sake, but for ours. We pray to remind ourselves that God is there and desires to guide our lives. By praising Him, it gets our focus on Him and the reality that He exists. Let us praise the One who knows all things about the past, present and future, because we believe and know that God is guiding our lives, therefore we should praise Him for that guidance.
Verse 1 begins by "exalting" God as one's King. To exalt someone means to hold that entity in very high regard. Yes, we acknowledge that God exists but we also submit to the fact He is in charge of our life. He is as David proclaims, "His King". Remember that David was a king himself and he understood the power of being a king. Yet, David in his role as a king thought of the God who created the universe as being his own King.
The last part of verse 1 says, I will bless thy name for ever and ever. Every believer ought to desire to praise God's name forever and ever. The obvious point is that David figured that he would exalt God as being in charge of his life not only for the rest of his life here on earth, but he wanted God to have that honor forever and into the next life.