in admin->settings->locations; that is where you add more countries/regions/cities to your database. not where you show it on the home page.
as the twitter default shows the regions already in the side bar, are you wanting to have regions selectable in the search bar? if so change this….
in theme/header.php
just after :
<div class="fill">
replace the entire container div with this:
<div class="container">
<?php osc_goto_first_category() ; ?>
<?php if(osc_count_categories () > 0) { ?>
<ul class="nav">
<?php while ( osc_has_categories() ) { ?>
<li class="<?php echo osc_category_slug() ; ?><?php if ( osc_count_subcategories() > 0 ) { ?> menu<?php } ?>">
<a href="<?php echo osc_search_category_url() ; ?>" <?php if ( osc_count_subcategories() > 0 ) { ?>class="menu"<?php } ?>><?php View::newInstance()->_erase('subcategories'); echo osc_category_name() ; ?></a>
<?php if ( osc_count_subcategories() > 0 ) { ?>
<ul class="menu-dropdown">
<?php while ( osc_has_subcategories() ) { ?>
<li class="<?php echo osc_category_slug() ; ?>"><a href="<?php echo osc_search_category_url() ; ?>"><?php echo osc_category_name() ; ?></a></li>
<?php } ?>
</ul>
<?php } ?>
</li>
<?php } ?>
</ul>
<?php } ?>
<ul class="nav secondary-nav btn success">
<li class="publish">
<a href="<?php echo osc_item_post_url_in_category() ; ?>"><?php _e("Publish your ad today", 'twitter'); ?></a>
</li>
</ul>
</div>