My sister arrived here in 1991 in a tourist Visa. She is single with no children. I am a Citizen now and I would like to sponsor her. Can I do it? How long does it take? Does she need to leave the country?
You shouldn't sponsor her, even though technically you can. First, the wait for a green card is about 12 years. Second she would have to leave the country; and she is now subject to the 10 year bar. It appears she will have a hrd time qualifying for a hardship waiver to allow her to re-enter the US after being out of status for so long.
You probably will want to contact a lawyer who can help explain other options to you.