How did sea power of the Phoenicians spread civilization?
The sea in the ancient world was very important, because it was one of the most important means for transportation. The Phoenicians were also some of the best sailor in the ancient world all the way up to the time of the Punic Wars with Rome (the Carthaginians were the heirs of the Phoenicians). Roman historians, such a Livy and Polybius make mention of this several times.
As for how the Phoenicians helped spread civilization, there are two chief ways.
First, the Phoenicians were able to contact many people through the sea. This created an interchange of goods. In a word, trade was made possible. This allowed people to share and exchange not only goods but also ideas. We must not underestimate this very important development.
Second, the Phoenicians were intellectuals and one of their greatest accomplishment was to give the concept of an alphabet to the Greeks. The Greeks, in turn, used this new invention and created some of the most enduring works in the Western canon. Think of the influence of people like Plato and Aristotle.