How to Add Read More Code in Theme Function [Wordpress]

Hi

From last 2 weeks im trying to add a feature as 250 words of post on page appear and rest of the article access by Read More Links in WORDPRESS

I have tried Tags and many tutorial but its seems my selected theme is not allowing or has bug in it. Alot of search I have found the following code which need to be add in function.php

<?php

add_filter( 'the_content_more_link', 'my_more_link', 10, 2 );

function my_more_link( $more_link, $more_link_text ) {
    return str_replace( $more_link_text, 'Continue reading &rarr;', $more_link );
}

?>

Code (markup):

Taken from

<?php

/**

* Coded by misbah (ini_misbah@yahoo.com)

*/

if ( function_exists('register_sidebar') ) {

    register_sidebar(array(

        'name' => 'Primary Sidebar',

        'before_widget' => '<li id="%1$s" class="widget">',

        'after_widget' => '</li>',

        'before_title' => '<h4 class="widget-title">',

        'after_title' => '</h4>',

    ));

    register_sidebar(array(

        'name' => 'Secondary Sidebar',

        'before_widget' => '<li id="%1$s" class="widget">',

        'after_widget' => '</li>',

        'before_title' => '<h4 class="widget-title">',

        'after_title' => '</h4>',

    ));

}

//Check for widgets in widget-ready areas http://wordpress.org/support/topic/190184?replies=7#post-808787

//Thanks to Chaos Kaizer http://blog.kaizeku.com/

function is_sidebar_active( $index = 1){

    $sidebars    = wp_get_sidebars_widgets();

    $key        = (string) 'sidebar-'.$index;

    return (isset($sidebars[$key]));

}

include(TEMPLATEPATH.'/includes/template-options.php');

include(TEMPLATEPATH.'/includes/plugins.php');

/*

add_action('widgets_init', 'remove_default_widgets', 0);

function remove_default_widgets() {

    if (function_exists('unregister_sidebar_widget')) {

        unregister_sidebar_widget('Search');

    }

}

include(TEMPLATEPATH.'/includes/widgets.php');

/**/

Code (markup):

If you have any suggestion then please give me thanks