diff --git a/GettingStartedOnTesting.wiki b/GettingStartedOnTesting.wiki
index 249de24..aabcba7 100644
--- a/GettingStartedOnTesting.wiki
+++ b/GettingStartedOnTesting.wiki
@@ -68,6 +68,20 @@
 It extends gaetestbed.mail.MailTestCase by subclassing unittest.TestCase so that all its subclasses need not subclass unittest.TestCase in their code and by overriding assertEmailSent method to extend its functions.
 === `TaskQueueTestCase` ===
 It extends gaetestbed.taskqueue.TaskQueueTestCase by subclassing unittest.TestCase so that all its subclasses need not subclass unittest.TestCase in their code.
+=== `Data seeder` ===
+Data are usually needed to conduct tests. The seed functions are here to seed data for tests. 
+  * There are two seed functions, seedn and seed. The difference between them is that seedn seeds n data of the model class while seed only seeds one data of the model class.
+  * Location: soc.modules.seeder.logic.seeder.logic.Logic
+  * Function prototype: seedn(self, model_class, n=1, properties=None), seed(self, model_class, properties=None)
+  * Usage: any number of properties can be specified either with their values or with the data provider used to generate the values. Unspecified properties will be generated randomly; unspecified ReferenceProperty will be generated and seeded recursively.
+    * model_class: data store model class
+    * n: number of entities to seed
+    * properties: a dict specifying some of the properties of the model_class objects to be seeded. The key of the dict is the name of the property. The value of the dict is either the value of the property or the data provider used to generate the value of the property, e.g.
+{{{
+        {"name": "John Smith", 
+         "age": RandomUniformDistributionIntegerProvider(min=0, max=80)}
+}}}
+  * For more detailed usage and examples, please check their documentations and their tests in tests.app.soc.modules.seeder.logic.seeder.logic.SeederLogicTest
 
 == Tools ==
 === pymox ===