How and why did the spanish build colonies in the new world?
Spain could have done it to obtain vast riches(silk,gold,velvet and spices) before another European country could.
The Spanish Crown wanted to increase its economic power and prestige in Europe.
After obtaining the wealth, it was now possible to build bigger, better ships for longer voyages. They owned more then half of north Americas land.
They were able to producing better and more accurate maps/charts of the world.
Since they were already tribes(Arawak, Caribs) in the new world, they enslaved them and began their colonization.