please help me. which station is near from New Shanhai Exhibition Center and how to get there? Xin Tian Di, Yuyuan Garden or the bund?

Your hotel is near the Longyang Road Station, right?
If so, you can walk to that station to take the subway line 2 to East nanjing Road Station. Get out of the station and walk to the Bund. From the East nanjing road station, you can take the subway line 10 to reach Yuyuan Garden Station. Get out of the station, you can walk to Yuyuan along the Fuyong Street.
From the Yuyuan Station, you can still take the line 10 to Xintiandi Station to get that place.