Why did spanish leaders want to push control into north america in the mid-1500s

Colonial expansion of the Spanish conquistadors was mainly for the purpose of trade and the spread of the Catholic faith and religion. The Spanish colonies started expanding across America starting in the year 1492. Half of South America, parts of Central America, Caribbean Islands, and North America were part of the colonies of Spain.

The reason why Spanish leaders wanted to push for control into North America in the mid-1500s was because they knew that there were probably more riches which they could exploit from this reagion; based on the knowledge they had had since the beginning of their conquests of the Americas. 

Basically create a schedule on what you need to study and stick with it