How to get to Senado Square

Hi,

I plan to spend a half day visit to Macau while staying in Hong Kong. How to get to Senado Square & the ruins of St. Paul's from Macau Ferry terminal? If I get a taxi how much would that cost? Which one is easier to visit first or I may not have time to visit both as I have to catch a 7.00 pm flight back to Jakarta from Hong Kong? Please help. Thanks to all.