Indigenous people were dying due to disease, plantations could not import enough cash crops to Europe even though they demanded for more. In order to solve this problem they turned their ships toward Africa.
Slaves were brought from Africa to the USA by Europeans to grow more cash crops. They traded textiles for these African Americans.
African Americans were forced to work without pay and in harsh conditions.
After Batista was overthrown by Fidel in 1959 (after many attempts) he took power. The USA backed Castro because he promised democracy but he later became a dictator as well.
Cuba traded with the Soviet Union, this may America angry and they placed an embargo with Cuba. This really hurt Cuba's economy and relations with both countries is now poor.
When Castro's health was not well he gave the power to younger brother Raul Castro who was is also a dictator.