a:active means when you click the link the css properties will apply on the link, instead of using a:active use
a.visited{color:red;}
Since you're just starting out, I'd suggest you use a library such as jQuery. So, if your HTML is like this:
<div id="box1" class="box">
<h3><a name="box1">something</a></h3>
</div>
<div id="box2" class="box">
<h3><a name="box2">something</a></h3>
</div>
<div id="box3" class="box">
<h3><a name="box3">something</a></h3>
</div>
And you have a CSS class called youarehere
:
.youarehere { color:white; background:green; }
With jQuery you could write something along the lines of:
$(".box > a").click(function() { // when clicking any of these links
$(".box > a").removeClass("youarehere"); // remove highlight from all links
$(this).addClass("youarehere"); // add highlight to clicked link
})
In plain JS, it takes a bit more effort to achieve this. Do yourself a favor and don't reinvent the wheel - people have already taken care of this, so use the product of their labor to make your life easier.
To change the link text color on mouse over use the following css:
<style type="text/css">
a:hover{color:Red;}
</style>