1-4: Habakkuk cried out to God, asking why He is idle in the face of so much violence and injustice in Judah.
5-11: God answers by telling Habakkuk that He'll raise up the Chaldeans as an instrument of judgment against Judah for it's iniquity. This was a prophecy of the coming Babylonian captivity. The Chaldean Dynasty reigned in Babylon in the 600's BC.
12-17: In light of God's response, Habakkuk questions why God would use an idolatrous nation even more wicked than Judah to judge them.
1: Habakkuk awaits God's response on a tower.
2-3: God commands Habakkuk to record His answer on tablets and wait for it to be fulfilled.
4-20: God describes the sins of the Chaldeans. In verses 7-8 and 16-17 He promises to judge the Babylonians as well by shaming and destroying them.
1-2: Habakkuk prays and affirms his fear of God then pleads for mercy in His wrath.
3-15: He praises God for His creation and for delivering His people in the past.
16: In fear, Habakkuk decides to quietly wait for God to judge the Babylonians who will invade them.
17-19: Though Habakkuk and his people will experience a time of judgement in captivity, he decides to rejoice in The Lord in these dark times, which are likened to a fig tree with no blossoms.