Example of how to add children to the homepage in ProcessWire in combination with the MarkupSimpleNavigation module. See: http://processwire.com/talk/topic/3065-direct-children-of-default-front-page/.

gistfile1.php

<?php
                            
    // Get the homepage
    $homepage = $pages->get("/");

    // Get all the homepage children who need to be under home in the menu
    $homePageChildren  = $homepage->children("homechild=1");
     
    // Store this in a variable so you can output it later
    $homeMenu = "<ul>";

    // Loop through the homepage children and store them in the var
    foreach($homePageChildren  as $homePageChild) {
        $homeMenu .= "<li><a href='{$homePageChild->url}'>{$homePageChild->title}</a></li>";
    }   
    $homeMenu .= "</ul>";
     
    // Start the actual menu here
    echo "<ul>";
     
    // Create the link to home and output the $homeMenu
    echo "<li><a href='{$homepage->url}'>{$homepage->title}</a>{$homeMenu}</li>";

    // Start Markup Simple Navigation
     $options = array(
        'parent_class' => 'parent', // string (default 'parent') overwrite class name for current parent levels
        'current_class' => 'current', // string (default 'current') overwrite current class
        'has_children_class' => 'has_children', // string (default 'has_children') overwrite class name for entries with children
        'levels' => false, // bool (default false) wether to output "level-1, level-2, ..." as css class in links
        'levels_prefix' => 'level-', // bool (default 'level-') prefix string that will be used for level class
        'max_levels' => 3, // int (default null) set the max level rendered
        'firstlast' => true, // bool (default false) puts last,first class to link items
        'collapsed' => false, // bool (default false) if you want to auto-collapse the tree you set this to true
        'show_root' => false, // bool (default false) set this to true if you want to rootPage to get prepended to the menu
        'selector' => 'homechild=0', // string (default '') define custom PW selector, you may sanitize values from user input
        'outer_tpl' => '', // template string for the outer most wrapper. || will contain entries
        'inner_tpl' => '<ul>||</ul>', // template string for inner wrappers. || will contain entries
        'list_tpl' => '<li%s>||</li>', // template string for the items. || will contain entries, %s will replaced with class="..." string
        'item_tpl' => '<a href="{url}">{title}</a>', // template string for the inner items. Use {anyfield} and {url}, i.e. {headline|title}, if field is of type image it will return url to image (first image if multiple)
        'item_current_tpl' => '<a href="{url}">{title}</a>' // template string for the active inner items.
    );

    // Output Markup Simple Navigation
    echo $treeMenu->render($options); 
     
    echo "</ul>";

  ?>