It is not quite clear from your question if you want to add node to main admin menu (horizontal one with fly-out sub-menus) or sidebar menu of System\Configuration
screen. Below are instructions how to add section, group and field to Magento configuration screen.
First you need the etc/system.xml
file to your module:
<?xml version="1.0"?>
<config>
<sections>
<your_module translate="label" module="your_module_shortcode">
<label>Your Module Name</label>
<tab>tab_id_where_you_want_to_add_your_section</tab>
<frontend_type>text</frontend_type>
<sort_order>980</sort_order>
<show_in_default>1</show_in_default>
<show_in_website>1</show_in_website>
<show_in_store>0</show_in_store>
<groups>
<your_group_name>
<label>Your Group Title</label>
<sort_order>10</sort_order>
<show_in_default>1</show_in_default>
<show_in_website>1</show_in_website>
<show_in_store>0</show_in_store>
<fields>
<your_field_name translate="label comment">
<label>Your Field Title</label>
<comment>Your Comment</comment>
<frontend_type>text</frontend_type>
<sort_order>10</sort_order>
<show_in_default>1</show_in_default>
<show_in_website>1</show_in_website>
<show_in_store>0</show_in_store>
</your_field_name>
</fields>
</your_group_name>
</groups>
</your_module>
</sections>
</config>
And then add the following section to your etc/adminhtml.xml
. It adds your newly created section to ACL so you will be able to control admin roles that can access it:
<config>
<acl>
<resources>
<admin>
<children>
<system>
<children>
<config>
<children>
<your_module translate="title" module="your_module_shortcode">
<title>Your Module Name</title>
</your_module>
</children>
</config>
</children>
</system>
</children>
</admin>
</resources>
</acl>
</config>