Edited whole document

docs/guide/helpers.md

 Helper Classes
 ==============
 
-Yii provides many helper classes to help simplify some common coding tasks, such as string/array manipulations,
-HTML code generation. These helper classes are organized under the `yii\helpers` namespace and
+Yii provides many helper classes to help simplify some common coding tasks, such as string or array manipulations,
+HTML code generation, and so forth. These helper classes are organized under the `yii\helpers` namespace and
 are all static classes (meaning they contain only static properties and methods and should not be instantiated).
-You use a helper class by directly calling its static method, like the following,
+
+
+You use a helper class by directly calling its static method:
 
 ```php
 use yii\helpers\ArrayHelper;
@@ -15,27 +17,20 @@ $c = ArrayHelper::merge($a, $b);
 Extending Helper Classes
 ------------------------
 
-Static classes are typically hard to customize because when you use them, you already hardcode the class names
-in your code, and as a result your customized versions will not get used unless you do some global replacement in your code.
-
-To solve this problem, Yii breaks each helper into two classes: one is base class (e.g. `BaseArrayHelper`)
-and the other the concrete class (e.g. `ArrayHelper`). When you use a helper, you should only use the concrete version.
+To make helper classes easier to extend, Yii breaks each into two classes: a base class (e.g. `BaseArrayHelper`)
+and a concrete class (e.g. `ArrayHelper`). When you use a helper, you should only use the concrete version, never use the base class.
 
-If you want to customize a helper, e.g., `ArrayHelper`, do the following steps:
+If you want to customize a helper, perform the following steps (using `ArrayHelper` as an example):
 
-1. Name your class the same as the concrete class provided by Yii, including the namespace part, e.g.,
-   `yii\helpers\ArrayHelper`;
-2. Extend your class from the base class, e.g., `class ArrayHelper extends \yii\helpers\BaseArrayHelper`;
-3. In your class, override any method or property as your want, or add new methods or properties;
-4. In your application that you plan to use your own version of the helper class, include the following
-   line of code in the bootstrap script:
+1. Name your class the same as the concrete class provided by Yii, including the namespace: `yii\helpers\ArrayHelper`
+2. Extend your class from the base class: `class ArrayHelper extends \yii\helpers\BaseArrayHelper`
+3. In your class, override any method or property as needed, or add new methods or properties
+4. Tell your application to use your version of the helper class by including the following line of code in the bootstrap script:
 
 ```php
 Yii::$classMap['yii\helpers\ArrayHelper'] = 'path/to/ArrayHelper.php';
 ```
 
-The Step 4 above will instruct Yii class autoloader to load your version of the helper instead of the one
-included in the Yii distribution.
+Step 4 above will instruct the Yii class autoloader to load your version of the helper class instead of the oneincluded in the Yii distribution.
 
-> Tip: You can also use `Yii::$classMap` to replace ANY core Yii class, not necessarily helper classes,
-> with your own customized version.
+> Tip: You can use `Yii::$classMap` to replace ANY core Yii class with your own customized version, not just helper classes.