first you must enable CTDB mode in your server options.
I cant remember which maps have db's off the top of my head, youll just have to experiment. They will show up on your radar as orange dots.
Collect them one by one by moving into them, you can throw or drop them using the mouse buttons.
Gather them all closely together and stand by them and press B to summon the dragon. Once Shenlong has been summoned you should get a menu offering wishes. You might have to press B again to show the menu i cant remember.
If my memory serves me right, you can wish for Strength (+1,000,000 PL), Immortality (temp invincibility), and Friendship (basically a point awarded for having summoned the dragon).
The dragonballs will scatter, and respawn after a certain period. They will go from stone to normal state after a bit more time.
If you install ECX rc2 dragonballs should be on every map, and generally all in the one spot. With ECX you have many more wish options. Keep in mind ESF is about skill over novelty, so dont expect people to be easy on you just so you can make a wish.