Add Magento admin functions: setting in the background (System/Configuration) to custom settings

<?xml version="1.0"?>
<config>
    <sections>
        <!--要加入的section的标识符，此处为sales, 也可以加入自己的section -->
        <sales>
            <groups>
                <my_settings translate="label">
                    <label>Settings 1</label>
                    <frontend_type>text</frontend_type>
                    <sort_order>500</sort_order>
                    <show_in_default>1</show_in_default>
                    <show_in_website>0</show_in_website>
                    <show_in_store>0</show_in_store>
                    <fields>
                        <enabled translate="label">
                            <label>Enabled</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>0</show_in_website>
                            <show_in_store>0</show_in_store>
                        </enabled>
                       <settings_2 translate="label">
                      <label>Settings2 </label>
                      <frontend_type>text</frontend_type>
                      <sort_order>2</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>0</show_in_store>
                     </settings_2 >
                    </fields>
                </my_settings>
            </groups>
        </giftcard>
    </sections>
</config>