system.xml

<?xml version="1.0"?>
<config>
  <tabs>
    <NAMESPACE translate="label" module="MODULE_NAME">
      <label>YOUR NEW SECTION</label>
      <sort_order>100</sort_order>
      <class>NAMESPACE</class>
    </NAMESPACE>
  </tabs>
  <sections>
    <NAMESPACE translate="label" module="MODULE_NAME">
      <label>SECTION NAME</label>
      <tab>NAMESPACE</tab>
      <frontend_type>text</frontend_type>
      <sort_order>100</sort_order>
      <show_in_default>1</show_in_default>
      <show_in_website>1</show_in_website>
      <show_in_store>1</show_in_store>
      <groups>
        <GROUP_IDENTIFIER translate="label">
          <label>GROUP NAME</label>
          <comment>This is the text that appears above the fields. It provides description for what the fields pertain to.</comment>
          <frontend_type>text</frontend_type>
          <sort_order>100</sort_order>
          <show_in_default>1</show_in_default>
          <show_in_website>1</show_in_website>
          <show_in_store>1</show_in_store>
          <fields>
            <TEXT_FIELD translate="label">
              <label>This is a text field</label>
              <frontend_type>text</frontend_type>
              <sort_order>100</sort_order>
              <show_in_default>1</show_in_default>
              <show_in_website>1</show_in_website>
              <show_in_store>1</show_in_store>
            </TEXT_FIELD>
            <BOOLEAN_FIELD translate="label">
              <label>This is a yes/no (boolean) selector</label>
              <frontend_type>select</frontend_type>
              <source_model>adminhtml/system_config_source_yesno</source_model>
              <sort_order>200</sort_order>
              <show_in_default>1</show_in_default>
              <show_in_website>1</show_in_website>
              <show_in_store>1</show_in_store>
            </BOOLEAN_FIELD>
          </fields>
        </GROUP_IDENTIFIER>
      </groups>
    </NAMESPACE>
  </sections>
</config>