Hi.

Actually, the Spanish monarchy was not keen on taking indigenous slaves in the New World, because they considered them subjects of their kingdom. They were more interested in converting them to Christianity. There was also a certain formula the conquistadors (who were very legalistic) had to follow before going to war with the natives. They had to read a document called the Requerimiento which proclaimed that the indigenous peoples were now Spanish subjects, requiring that they convert to Christianity. Then, the Spanish would hand them a Bible.

Now, imagine for a moment, if you will, that a group of oddly-colored men say something in a language you have never heard before and hand you an object that seems useless. You don't know how to read and write; even if you did, you do not read Castilian or Latin. What would you do with it? You'd probably chuck it, seeing as it looks pretty useless.

Then the Spanish would be able to claim that the indigenous people had rejected Christianity and go to war, which was considered just at that time.

Later, a system called "encomienda" was set up. In this system, Spanish men would take charge of a group of indigenous. In exchange for teaching them Spanish and catechism, the Spanish were allowed to use them as labor. As you can imagine, this system was often abused.

For the Taino, though, the main killer was disease. Even though there were some wars (which the Spanish often lost; the first colony founded by Columbus, Navidad, was completely destroyed by Taino or Arawak such that they couldn't even locate it), the main killer was diseases that the Taino and other New World peoples had no resistance to. These epidemics killed about 75% of all indigenous people and something like 95% of the Tainos. It was even more devastating than the plague had been to Europe.

It is now believed that had the Aztecs not been ravaged by European diseases, they could probably have beaten the Spanish quite handily.