You can make use of the family-based green card process to apply a green card for your brother or sister. If you are a U.S. citizen, you should have gained your citizenship through naturalization or citizenship process, and you should be above 21 years of old to petition a green card for your sister or brother. Through the family-based green card process once your sister or brother enters the United States they are eligible to work permanently and later apply for citizenship. And you cannot apply for a green card for your sister or brother through family-based green card process if you are a green card holder.
The family-based green card process is a multi step process. First your need to file an Immigration petition using Form I-130 with USCIS. After USCIS approves the Form I-130, an immigrant visa number should be available. Once the immigrant visa is available they will be notified to go and schedule an interview in their local U.S. consulate. If your brother or sister is already in the U.S. on a different visa you can file I-130 later once the immigrant visa number becomes available they can apply for adjustment of status in the United States.
You needn’t file separate Form I-130 for your sister or brother. You can use a single Form I-130 and file for all your eligible sisters and brothers. Along with form I-130 you will need to file Form I-864 Affidavit of Support to establish that you have enough income to support your siblings.
You will have to submit the supporting document along with Form I-130 to establish your relationship, and each supporting document varies based on your situation.
If you and your sibling have same mother you need to file Form I-130, with your birth certificate and your siblings birth certificate with your mother’s name on it along with your proof for citizenship and affidavit of support.
If you and your sibling have same father but different mother, then you will have to file Form I-130 with your birth certificate with your father’s name and your siblings birth certificate with your father’s name, a copy of divorce decree or any documents to prove your fathers previous marriage were ended.