The Chu Rua quest is part of the Tutorial, it's a new players first chance for a legend mark.
It comes after you've done a few of the other tutorial quests, and begins when the tutor in your city says this:
After you choose yes, he sends you somewhere else.
Once there, you need to go find and talk to this extremely long winded turtle:
He will talk.. for a really long time. He will say many things that will seem very pointless... but if you're still paying attention at the end, he will say something almost useful.
"Skip" North(you can just walk if you want to, north is up by the way) and you will see this lovely little snob of a rabbit.
If you say 'Hello' to the rabbit, as the turtle suggested... he wont say a whole lot. but he'll ask you what you want! You want Ginseng. Tell him that, and he'll whine, but tell you which way to go. So continue on your way North.
Next, you'll see this rock..
Feel free to say 'Hello' to it as well. It's a friendly rock, it'll give you a helpful tip about what to do with the Tiger up North... So, go North again and meet Mr.Tiger!
Go ahead and say 'Hello' to the Tiger, just so you can say you said it to all of them, then ask him about the Ginseng. He doesn't seem to eager to help, so go ahead and mention the Rabbit as the Rock suggested. Tell him he's in the Forest, and the Tiger will run off.
After that, go on up to the top left corner and you should find the ginseng. Take it back to the turtle and you'll get a Sea Ring, a Legend mark, a Karma raise, and 400 exp. Hurray for your first Legend mark and possibly first hand item!