Since Zen is the most valueable Currency it is also the hardest one to earn.
There are 3 methods that can be used.
1. Buy Zen for real money by becoming a gold member.
2. Get 8000 Dilithium Ore per day and turn it into Refined Dilithium; this Refined Dilithium can then be traded with Zen -> exchange rates vary (currently about 1:150); so with other words you can get about 50 Zen per day
3. Earn Zen on the perfect world website by taking part in surveys or other stuff. Personally I would advice you not to take part in anything that requires registration or where you have to enter your email addy. From time to time there are good offers that you can take... some free surveys... watching videos or stuff where you only need to click a link to get your zen.
My advice for everything else... dont do it.
Why is Zen so important?
Well... there are some ships that you can buy only for zen... and there are lockboxes with special contents that you can only open if you buy a key with zen.
Additionally there are other features which needs to get unlock by paying zen such as bigger inventories.
