Adding icon to <li> menu

[admin]

<blockquote>
i am working on a school project and I am stuck at a point where i
want to put an image ( >>&lt;&lt; ) inbetween

<li>

-tags. Because it's a
navigation in wordpress it's done in php.

Here is what i have:

<a href="http://img825.imageshack.us/img825/253/screenshot20120529at305.png" rel="nofollow noreferrer">img http://img825.imageshack.us/img825/253/screenshot20120529at305.png</a>

Here is what i want (look at the blue thingies in between the menu
items):

<a href="http://img703.imageshack.us/img703/253/screenshot20120529at305.png" rel="nofollow noreferrer">img http://img703.imageshack.us/img703/253/screenshot20120529at305.png</a>

I think this is the php where i need to put my image/menuitem.png..
but where? Help would very much be appreciated

function inkthemes_nav() {
    if (function_exists('wp_nav_menu'))
        wp_nav_menu(array('theme_location' => 'custom_menu', 'container_id' => 'menu', 'menu_class' => 'ddsmoothmenu',

'fallback_cb' => 'inkthemes_nav_fallback'));
else
inkthemes_nav_fallback();
}

function inkthemes_nav_fallback() {
    ?>
    <div id="menu">
        <ul class="ddsmoothmenu">
            <?php
            wp_list_pages('title_li=&show_home=1&sort_column=menu_order');
            ?>
        </ul>
    </div>
    <?php
}

function inkthemes_home_nav_menu_items($items) {
    if (is_home()) {
    //home
        $homelink = '<li class="current_page_item">' . '<a href="' . home_url('/') . '">' . __('Home', 'themia') . '</a></li>';
    } else {
     //niet home
        $homelink = '<li>' . '<a href="' . home_url('/') . '">' . __('Home', 'themia') . '</a></li>/>';

    }
    $items = $homelink . $items;
    return $items;
}

</blockquote>