The main event of New Years Eve is traditionally associated with the date on the Gregorian calendar of the 31st December, but in China they started counting years a lot sooner, and their calendar works on a rotating basis, with the date therefore moving each year.
Each year is associated with a different animal, and the year you're born in denotes the animal you are forever destined to be associated with - in 2018 the celebrations will be to welcome the Year of the Dog.
I was fortunate to be born in the Year of the Tiger, which is one of the best options I think - probably only the dragon would be a little cooler! Chinese New Year, or CNY as it is commonly abbreviated to, in 2019 takes place on the 8th February, which marks the beginning of the Year of the Monkey, so expect simian costumes to feature heavily in any parades you might be going to.
The main celebrations of course take place in the big cities of China - Beijing, Shanghai and the like, as well as the newly repatriated colony of Hong Kong, where the Victoria Harbour fireworks are some of the most spectacular you will see anywhere, for any occasion!
There are also parades, fireworks and celebrations in large cities around the world where there are significant Chinese populations, including Boston, New York and San Francisco in the USA in particular. Elsewhere, Singapore holds the famous Chingay Street Parade to mark the occasion.
For more details of particular events in specific locations, see the links below.