To him who rides on the heaven of heavens

The word "Sing" is implied as the beginning of this verse. Here God is described as if he rides in a chariot in the sky. Alternate translation: "Sing to God who rides across the sky in his chariot" (See: rc://en/ta/man/translate/figs-ellipsis and rc://en/ta/man/translate/figs-metaphor)

he lifts up his voice with power

This idiom means he speaks powerfully. Alternate translation: "he shouts powerfully" or "he speaks loudly" (See: rc://en/ta/man/translate/figs-idiom)