Sorry for a long response - Hope this helps
If the person is already lawfully in the U.S., they can file Form I-485 (Adjustment of Status) to become a permanent resident:
They can usually file I-485, I-765 (work permit), and I-131 (advance parole) all together.
Once I-485 is approved, they get the green card.
Work and travel permits typically arrive within 3–6 months; green card in about 6–12 months.
If the person is outside the U.S., they’ll go through Consular Processing:
NVC (National Visa Center) contacts them for further processing.
They’ll pay fees, submit the DS-260 immigrant visa application, provide civil documents, and attend a medical exam.
Eventually, they attend an interview at a U.S. Embassy or Consulate.
If approved, they’ll receive an immigrant visa to enter the U.S. as a permanent resident.