Sample Magento system.xml, which defines System > Configuration options

system.xml

<?xml version="1.0"?>
<!--
/**
 * Magento admin configiguration section config
 *
 * @author Magento
 */
-->
<config>
    <sections>
        <news>
            <class>separator-top</class>
            <label>News</label>
            <tab>general</tab>
            <frontend_type>text</frontend_type>
            <sort_order>500</sort_order>
            <show_in_default>1</show_in_default>
            <show_in_website>1</show_in_website>
            <show_in_store>1</show_in_store>
            <groups>
                <view translate="label">
                    <label>News View Settings</label>
                    <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>1</show_in_store>
                    <fields>
                        <enabled translate="label">
                            <label>Enable News On Frontend</label>
                            <frontend_type>select</frontend_type>
                            <source_model>adminhtml/system_config_source_yesno</source_model>
                            <sort_order>10</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>1</show_in_store>
                        </enabled>
                        <items_per_page translate="label">
                            <label>News Per Page</label>
                            <comment>Empty value is the same as default 20.</comment>
                            <sort_order>30</sort_order>
                            <depends><enabled>1</enabled></depends>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>1</show_in_store>
                        </items_per_page>
                        <days_difference translate="label">
                            <label>Number of days since a post has been marked as recently added</label>
                            <comment>Empty value is the same as default 3.</comment>
                            <sort_order>50</sort_order>
                            <depends><enabled>1</enabled></depends>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>1</show_in_store>
                        </days_difference>
                    </fields>
                </view>
            </groups>
        </news>
    </sections>
</config>