"Selah" is usually thought to mean "pause and reflect" and might have been a place for a musical interlude for emphasis. I love to read this meditatively, and pause where the text suggests it.
Psalm 77: The Consoling Memory of God’s Redemptive Works
I cried out to God with my voice—
To God with my voice;
And He gave ear to me.
2 In the day of my trouble I sought the Lord;
My hand was stretched out in the night without ceasing;
My soul refused to be comforted.
3 I remembered God, and was troubled;
I complained, and my spirit was overwhelmed. Selah
4 You hold my eyelids open;
I am so troubled that I cannot speak.
5 I have considered the days of old,
The years of ancient times.
6 I call to remembrance my song in the night;
I meditate within my heart,
And my spirit makes diligent search.
7 Will the Lord cast off forever?
And will He be favorable no more?
8 Has His mercy ceased forever?
Has His promise failed forevermore?
9 Has God forgotten to be gracious?
Has He in anger shut up His tender mercies? Selah
10 And I said, “This is my anguish;
But I will remember the years of the right hand of the Most High.”
11 I will remember the works of the Lord;
Surely I will remember Your wonders of old.
12 I will also meditate on all Your work,
And talk of Your deeds.
13 Your way, O God, is in the sanctuary;
Who is so great a God as our God?
14 You are the God who does wonders;
You have declared Your strength among the peoples.
15 You have with Your arm redeemed Your people,
The sons of Jacob and Joseph. Selah
16 The waters saw You, O God;
The waters saw You, they were afraid;
The depths also trembled.
17 The clouds poured out water;
The skies sent out a sound;
Your arrows also flashed about.
18 The voice of Your thunder was in the whirlwind;
The lightnings lit up the world;
The earth trembled and shook.
19 Your way was in the sea,
Your path in the great waters,
And Your footsteps were not known.
20 You led Your people like a flock
By the hand of Moses and Aaron.