For every settings page you'll need to use the Form API to allow the user to add/edit the configuration values. This is a simple example of the form and the submit function.

/**
 * Form builder: Create and display the configuration settings form.
 */
function MY_MODULE_NAME_form($form, &$form_state) {
  
  // Select List Count
  $form['MY_MODULE_NAME_setting1'] = array(
    '#type' => 'textfield',
	'#default_value' => variable_get('MY_MODULE_NAME_setting1','Default Value'),
	'#title' => t('Setting 1'),
	'#description' => t('Add a value for Setting 1 here.'),
	'#size' => 60,
	'#maxlength' => 60,
	'#required' => TRUE,
  );
  
  // Submit Button
  $form['submit'] = array(
    '#type' => 'submit',
	'#value' => t('Save Settings'),
  );
  
  return $form;
}

/**
 * Save configuration settings for MY_MODULE_NAME module.
 */
function MY_MODULE_NAME_form_submit($form, &$form_state) {
  variable_set('MY_MODULE_NAME_setting1', $form_state['values']['MY_MODULE_NAME_setting1']);
  
  drupal_set_message('The MY_MODULE_NAME settings have been saved at '.date("d/m/Y H:i:s"));
}