If I got residency in Spain can I visit the states...

We would like to inform you that the Visa Waiver Program allows citizens of some countries, including Spain, but not residents, to travel to the United States of America for tourism or business (for visitor visa purposes) for a stay of 90 days or less without obtaining a visa. It is worth noting that some countries do not participate in the Visa Waiver Program and some travelers from Visa Waiver Program countries are not eligible to use the program. Visa Waiver Program travelers are required to apply for a permit through the Electronic System for Travel Authorization (ESTA), and such travelers are screened at the US port of entry and enrolled in the US Department of Homeland Security's US Visit Program.
And then you must obtain a visa to enter the United States because you are not a Spanish citizen