What are the main places to see in Macau, and how is the night life

The major attractions are Fisherman Wharf, Macao Tower, Venetian Resort, Senado Square, the local Museum and Ruins of St. Pauls.

As it is a Gamblers' Paradise, the nightlife there mainly gathers in these relevant places. Anyway, you can have more experience. Just check this link to get more info:
https://www.travelchinaguide.com/cityguides/macau/nightlife.htm