Or, at least it helps me to work for xiaonei.com...
OK, come back to the point. Just follow the instruction on facebook. But several things remain to stop me from doing that. Several lessons:
* Use a host that supports php5 (or, maybe php4 is good enough?). I used godaddy's economical hosting, whose default configuration (IIS6) doesn't support php at all. Fortunately it provides a free (!!) update to IIS7 which works for php5. That confused me quite a while.
* Be careful for the settings:
- Call back URL. Make sure to end with a "/" at last.
- Use a IFrame to start with, and you can see the results for even a single HTML source page. Then be careful to change to FBML.
- When using FBML, write a index.php and write code to that file. Now I'm using the example provided by facebook (Get started quickly with some example code) which is a php code (FBML also works).
Gotta move on. Add oil!