halfhuman on "Insert new input field"

How do I add new input field on this code?

public function form( $instance )
    {
        $user_id = isset ( $instance['user_id'] ) ? $instance['user_id'] : array();
		$user_id_num = count( $user_id );
		$user_id[ $user_id_num + 1 ] = '';
		$user_html = array();
		$user_id_counter = 0;

		foreach (array_values($user_id) as $name => $value)
		{
			$user_html[] = sprintf(
				'User ID<br/><input type="text" name="%1$s[%2$s]" value="%3$s" class="widefat">',
				$this->get_field_name( 'user_id' ),
				$user_id_counter,
				esc_attr( $value )
			);
			$user_id_counter += 1;
		}

        print 'New User' . join( '<br /><br />', $user_html );
    }

Basically I wanted to add new input field Location right next to the User ID field and then change the foreach so it also get the new user_location. How to I rewrite the code to achieve what I wanted?