added "Usage" section to README

README.md

@@ -68,3 +68,99 @@ class SiteController extends Controller
     }
 }
 ```
+
+Usage
+-------------
+1) Creating a Controller
+
+First, create a controller class `app\controllers\UserController` as follows:
+
+```php
+namespace app\controllers;
+
+use yii\rest\ActiveController;
+
+/**
+ * Class UserController
+ */
+class UserController extends Controller
+{
+    /**
+     * @SWG\Get(path="/user",
+     *     tags={"User"},
+     *     summary="Retrieves the collection of User resources.",
+     *     @SWG\Response(
+     *         response = 200,
+     *         description = "Category collection response",
+     *         @SWG\Schema(ref = "#/definitions/User")
+     *     ),
+     * )
+     */
+    public function actionIndex()
+    {
+        $dataProvider = new ActiveDataProvider([
+            'query' => User::find(),
+        ]);
+
+        return $dataProvider;
+    }
+}
+```
+The controller class extends from `yii\rest\ActiveController`, which implements a common set of RESTful actions. 
+
+2) Creating `User` definition
+
+You need to create folder `definitions` and add `User` definition class as follows:
+
+```php
+<?php
+
+namespace api\models\definitions;
+
+/**
+ * @SWG\Definition(required={"username", "email"})
+ *
+ * @SWG\Property(property="id", type="integer")
+ * @SWG\Property(property="email", type="string")
+ * @SWG\Property(property="username", type="string")
+ */
+class User
+{
+}
+```
+
+3) Configuring URL Rules
+
+Then, modify the configuration of the urlManager component in your application configuration:
+```php
+'urlManager' => [
+    'enablePrettyUrl' => true,
+    'enableStrictParsing' => true,
+    'showScriptName' => false,
+    'rules' => [
+        'GET,HEAD users' => 'user/index',
+    ],
+]
+```
+
+4) Enabling JSON Input
+
+To let the API accept input data in JSON format, configure the parsers property of the request application component to use the `yii\web\JsonParser` for JSON input:
+```php
+'request' => [
+    'parsers' => [
+        'application/json' => 'yii\web\JsonParser',
+    ]
+]
+```
+
+Trying it Out
+-------------
+
+Now you can access to swagger documentation section through the following URL:
+
+http://localhost/path/to/index.php?r=site/docs
+
+
+
+