As a citizen or permanent resident of the United States, you may help a foreign relative obtain a Green Card. To do so, you need to sponsor your relative and also prove that you have enough income or assets to support your relative when they come to the United States. Form I-130 is used to establish your relationship to the relative you want to sponsor.
If your relative lives abroad, you must first file Form I-130 with USCIS. You will also need to submit evidence of your U.S. citizenship or permanent residence, and evidence proving your relationship to each person for whom you want to sponsor. Filing Form I-130 gives your relative a place in line with others waiting to immigrate from the same country or region based on the same type of relationship. There is no waiting period for immediate relatives of U.S. citizens, which includes spouses, parents, or unmarried children under age 21. Other types of relatives (or relatives of permanent resident sponsors), may have to wait several years while petitions that were filed before theirs are processed. When a visa number becomes available for your relative, the U.S. Department of State will contact your relative and extend invitation to him or her to apply for an immigrant visa. Your relative should not enter the U.S. before this invitaiton is extended.
If your relative is already in the United States and entered legally, then they may be able to file Form I-485, Application to Adjust Status, at the same time that you file the Form I-130. This should speed up the process of obtaining a Green Card for your relative.