There are two main paths toward applying for Permanent Resident Status ("green card"), and ultimately Citizenship, in the United States: through family-based or employer-based sponsorship.
With family-based sponsorship, certain family members may apply on behalf of a relative depending on their U.S. immigration status and relationship to the beneficiary.
Employment-based sponsorship requires that a U.S. company sponsors you for Permanent Resident Status based on your current position or a future position offered to you. Strict requirements apply under regulations by both the U.S. Citizenship and Immigration Services (CIS) and the U.S. Department of Labor (DOL).