American Scholarship

For graduate work in the US you will want a fellowship or an assistantship, not a scholarship. Scholarships are for undergraduate work.

In general you get your fellowship or assistantship through the department in which you are pursuing your advanced degree. So, apply to a number of graduate programs at universities that have a field you want to specialize in. As part of that application process they will likely send you forms for you to request financial help.

Also in general, a fellowship will be money paid to you for you do do research, usually for your academic advisor. An assistantship is money paid to you to teach introductory classes in your field.

Your advisor at your present school should be able to get you started in this process, or else the chairman of your department. Your advisor or department chairman may know of other independent sources of monies for fellowships.