If you need a general introduction to the game of Chinese Checkers, you can take a look here: Wikipedia
china.io supports a few different ways of playing: You can play the fast-paced variant ("long jumps") or the basic variant ("short jumps"). You can play with just two colors (one for you and one for the program), or you can play with all six (three colors each).
How to get started:
Unless you specify the opposite, you are the one to move first. You always play from South to North; the program from North to South. A colored arrow head indicates which color that's the one move. When you want the program to do its move, you type M. There may also be situations when it's your turn and there's no move you can do; then you must also use M to pass the control to the next color. Use the Help function (type H or ?) to get information about other useful commands.
In the chinaConfig.io file you can adjust a few properties. You can enter your name, change the background color, change the size of the board graphics and the size of the window. You can also specify whether you want "all colors" or "long jumps" to be your defaults. When tuning the background color (or the size of the board graphics), you don't have to quit and restart china.io to see the effect; if you type C, the chinaConfig.io file will be reloaded. To quickly find the best looking size of the board graphics, you can use the left and right arrow keys on the keyboard.
Even if the moves that the program makes sometimes may be quite impressive, the program is actually not that smart. The current (1.4) version doesn't look ahead at all, it just tries to find a move with a reasonably good "gain" value. This works quite well, but in the final part of a game you will probably notice its weakness (and stupidity).
If for some reason you'll want to relax the rules a bit, you can type D to get into "developer mode". Then you can do things like move the pieces belonging to the program, let the program move (M) yours, Undo (Z) as many moves as you like, and reveal all possible moves in the current situation (with r you'll see the best ones first; R will cycle the other way).
Have fun!
Jon Kleiser, 15-Aug-2005