At times we need to add new configurations options or modify some option in an existing module, lets see how to do it in this article. Suppose we have to add a new field “Surcharge” to the Payment Method “Cash on Delivery” configuration options and modify the “Instructions” option label to “Message”.

To do this we have to create a new module.

1. We create a file “Techawaken_Cod.xml” in folder app\etc\modules\ to declare the module. The content of the file is shown below:

<?xml version="1.0"?>
<config>
<modules>
<Techawaken_Cod>
<active>true</active>
<codePool>local</codePool>
<depends>
<Mage_Payment />
</depends>
</Techawaken_Cod>
</modules>
</config>

2. Next we create the module folder structure app\code\local\Techawaken\Cod\etc\

3. Now create a system.xml file in the folder app\code\local\Techawaken\Cod\etc\ with the following contents

<?xml version="1.0"?>
<config>
<sections>
<payment translate="label" module="payment">
<groups>
<cashondelivery translate="label">
<fields>
<surcharge translate="label">
<label>Surcharge</label>
<frontend_type>text</frontend_type>
<sort_order>62</sort_order>
<show_in_default>1</show_in_default>
<show_in_website>1</show_in_website>
<show_in_store>1</show_in_store>
</surcharge>
<instructions translate="label">
<label>Message</label>
<frontend_type>textarea</frontend_type>
<sort_order>62</sort_order>
<show_in_default>1</show_in_default>
<show_in_website>1</show_in_website>
<show_in_store>1</show_in_store>
</instructions>
</fields>
</cashondelivery>
</groups>
</payment>
</sections>
</config>

The original configuration options for the “Cash On Delivery Payment” method are defined in system.xml file located at app\code\core\Mage\Payment\etc\. Compare the <cashondelivery>  group with the above code to study the changes made.

4. Now flush the caches and reload the admin configuration page, you will notice the changes/additions made.

If you do not want to create a new module then you can skip step 1 and add the code mentioned in step 3 above to system.xml file of some custom module already created.