How did Spanish Conquistadors conquer the Aztec Empire?

After a three month siege, Spanish forces under Hernàn Cortés capture Tenochtitlán, which is the Capital of the Aztec empire. Cortés leveled the city and captured Cauhtémoc, which was also the Aztec empire. In 1511, he sailed with Diego Velásquez to conquer Cuba twice. Which is now called the Hispaniola