Sang Lan, the 17-year-old Chinese gymnast paralyzed in a fall at last summer’s Goodwill Games, will help Mayor Rudolph Giuliani ring in the new year at Times Square. Lan will help drop the ceremonial lighted ball, an annual tradition watched by approximately 250 million TV viewers. Thousands of people pack Times Square to watch the ball descend a 77-foot flagpole for one minute, until it reaches the bottom at midnight. “This is a special honor, not only to me but also to the Chinese people,” Lan said this week, smiling and waving from her wheelchair. “I love New York. I love you all.” Lan was chosen for “her courage and great good cheer” in dealing with the injury she suffered July 21, said Brendan Sexton, head of the Times Square Business Improvement District.