God's power and works are praised in this Psalm.
The grouping of verses before the first "selah" (v4) are a call to fill the earth with the praise of God. Tell everyone of His goodness so that all the earth will praise Him.
The group of scriptures before the second "selah" (v7) are an invitation for all to come see the works of God. The church should take note that it is not the works of man which we invite the world to see. If they came to one of our services, would they see the works of God or the works or man?
The next group of verses, ending with the third "selah" (v.15) focuses on the personal and corporate relationship of God and His people. He is with us in trials and He brings out!
The final group of verses through the end of this Psalm are a personal testimony of answered prayer.