I feel it may be easier for me to achieve this by editing the actual HTML/PHP files - I just don't know what I need to edit and where....
For the most part this does not exist as you might be thinking.and therefore there is not a complete page that you can edit like you would for a html site. The high side of this is that ou do not have to maintain the many pages that a html site requires as each page is built dynamically from the defined pieces. Down side - you need to grasp where these pieces are defined/customized.
My suggestion to you would be to NOT mess with the live site directly. Create another install with it's own DB in another directory. Then you can make your attempts to change things without worring about bringing the live site down. And when you are confident that you have your alterations down and know which files are changed/added and where to make them function it is easy to move just these to the live site.
The previous individual has created a custom template named "classic2" and you should breif youself on the ins & outs of the override system to maintain this and your edits to files. This information is in the FAQ's and the wiki here.
To add what you want - the design of this site has employed a table for the top links with the following code:
Code:
</td>
</tr>
</table>
<table border="0" cellspacing="0" cellpadding="0" class="headerNavigation" align="center">
<tr class="headerNavigation">
<td align="left" valign="top" width="60%" class="headerNavigation">
<a href="http://noahsarkbikes.co.uk/zencart/index.php?main_page=index&../../classic/common">Home</a>|
<a href="http://www.noahsark.co.uk/newshop/">New Shop</a>|
<a href="http://www.noahsark.co.uk/blog/">Blog</a>|
<a href="http://noahsarkbikes.co.uk/zencart/index.php?main_page=contact_us/">Contact Us</a>|
<a href="https://noahsarkbikes.co.uk/zencart/index.php?main_page=login&../../classic/common">Log In</a>
</td>
<td align="center" width="0%"></td>
<td class="headerNavigation" align="right" valign="top" width="50%">
</td>
</tr>
</table>
It appears that they have not utilized the tpl_header.php file and the associated div's contained in that file like:<div id="headerWrapper"> and <div id="logoWrapper">
Not the way I would have done it but then it does work. You would have to add your additional link to the code that they have defined for this nav bar which is not part of the Zen Cart files as distributed.