How to register new widget field

in the funcion.php

register_sidebar( array(
'name' => 'Footer Sidebar one',
'id' => 'footer-sidebar-one',
'description' => 'Appears in the footer area',
'before_widget' => '<aside id="%1$s" class="widget %2$s">',
'after_widget' => '</aside>',
'before_title' => '<h3 class="widget-title">',
'after_title' => '</h3>',
) );

in the theme file (footer.php, sidebar.php, etc )

<div id="footer-sidebar" class="secondary">
<div id="footer-sidebarone">
<?php
if(is_active_sidebar('footer-sidebar-one')){
dynamic_sidebar('footer-sidebar-one');
}
?>
</div>