如何激活现有的水平菜单？

can someone help me with horizontal menu? I want make acive page on this menu, I thing i need add new class to css file. I hope u understand me. Thanks

This is what i have now: menu-theme2.css

    <ul class="theme2">
        <li><a href="index.php"><span>HOME</span></a></li>
        <li><a href="kredity.php"><span>KREDITY</span></a></li>
        <li><a href="shop.php"><span>SHOP</span></a></li>
        <li><a href="aukce.php"><span>AUKCE</span></a></li>
        <li><a href="servery.php"><span>SERVERY</span></a>
        <li><a href="forum"><span>FORUM</span></a></li>
    </ul>

And i want this on index.php:

        <ul class="theme2">
        <li><a class="active" href="index.php"><span>HOME</span></a></li>
        <li><a href="kredity.php"><span>KREDITY</span></a></li>
        <li><a href="shop.php"><span>SHOP</span></a></li>
        <li><a href="aukce.php"><span>AUKCE</span></a></li>
        <li><a href="servery.php"><span>SERVERY</span></a>
        <li><a href="forum"><span>FORUM</span></a></li>
    </ul>

Try to something like this.

For horizontal menu you can put below css rules in your css file.

.theme2 li {
    float: left;
    list-style: outside none none;
    margin-left: 10px;
}

For active class.

 $(function(){
    var url = window.location.pathname;
    alert(url);
    urlRegExp = new RegExp(url.replace(/\/$/,'') + "$"); 
    // create regexp to match current url pathname and remove trailing slash if present as it could collide with the link in navigation in case trailing slash wasn't present there
    // now grab every link from the navigation
    $('.theme2 ul li a').each(function(){
    // and test its normalized href against the url pathname regexp
        if(urlRegExp.test(this.href.replace(/\/$/,''))){
            $(this).addClass('active');
        }
    });
  });

index.php
<?php $page = "index"; ?>
shop.php
<?php $page = "shop"; ?>
<ul>
<li><a <?php if($page == 'index') {echo 'class="active"';} ?> href="index.php"><span>HOME</span></a></li>

 <li><a <?php if($page == 'shop') {echo 'class="active"';} ?> href="index.php"><span>SHOP</span></a></li>
</ul>

Following Nikit's solution, you can do the following without setting the $page variable value in each page, using PHP's __FILE__ constant:

<ul>
<li><a <?php if(basename(__FILE__, '.php') == 'index') {echo 'class="active"';} ?> href="index.php"><span>HOME</span></a></li>

 <li><a <?php if(basename(__FILE__, '.php')== 'shop') {echo 'class="active"';} ?> href="index.php"><span>SHOP</span></a></li>
</ul>