As a green card holder, you cannot sponsor your sister. First, become a US citizen through naturalization, then file Form I-130 to sponsor your sister.

Once you're a US citizen, file Form I-130, Petition for Alien Relative, to sponsor your sister. She'll need to wait for a visa number to become available, which may take several years.

Consider consulting an immigration attorney to explore other options, such as humanitarian parole or other forms of relief, which may be available depending on your sister's specific circumstances