Magento custom module blocks and config.xml help

Question

I have created a custom module but having a little difficulty with blocks in the config.xml

For some reason I'm not able to get the blocks to show on the dump of all the xml...maybe I've missed something?

I have the following structure:

app\code\local\Site\SiteTest\etc\config.xml

app\code\local\Site\SiteTest\Block\test.php

<?xml version="1.0" encoding="UTF-8"?>
<config>
    <modules>
        <Site_Test>
            <version>1.0.0</version>
        </Site_Test>
    </modules>  
    <global>
        <blocks>
            <highest>
                <class>Site_Block</class>
            </highest>
        </blocks>
    </global>
</config>

I am trying to link this to a custom layout for example:

<block type="sitetest/test" name="home.catalog.product.test" template="catalog/product/test.phtml" after="cms_page">

If anyone could shed some light on this would really be appreciated.