Where in admin sidebar?

You need to snip the metabox code on function.php file, this is the example code for the single metabox

add_action( 'admin_init', 'rw_register_meta_box' );
function rw_register_meta_box()
{
    // Check if plugin is activated or included in theme
    if ( !class_exists( 'RW_Meta_Box' ) )
        return;
    $prefix = 'rw_';
    $meta_box = array(
        'id'       => 'personal',
        'title'    => 'Personal Information',
        'pages'    => array( 'post', 'page' ),
        'context'  => 'normal',
        'priority' => 'high',
        'fields' => array(
            array(
                'name'  => 'Full name',
                'desc'  => 'Format: First Last',
                'id'    => $prefix . 'fname',
                'type'  => 'text',
                'std'   => 'Anh Tran',
                'class' => 'custom-class',
                'clone' => true,
            ),
        )
    );
    new RW_Meta_Box( $meta_box );

or you can find more details on the readme.txt or here:

Hope this helps