A short disclaimer: I am not allowed to provide consulting services regarding obtaining U.S. citizenship. For this process I recommend visiting the U.S. Citizenship and Immigration Services page and visiting the citizenship tab.
Check out my interactive map on seeing if you are eligible for visa free access to the U.S. If not then look into applying for a visa under the Travel.State.Gov webpage. This site is great is it also very user friendly and can make visa your processes seamless.
The U.S. has a a few more ‘dependencies’ they are: Puerto Rico, U.S. Virgin Islands, American Samoa, Guam, Northern Marina Islands. Where you can also work and live indefinitely. Office of Insular Affairs breaks down the information quite nicely!