When you say template, what exactly do you mean? Is it just visual or is it something with function? The link you gave makes it seem like it’s just a picture. For turning it into a theme, you have many options. What comes to mind first is that you basically have to decide where you want to define your main sections (kinda like making slices for optimizing an image) for your header, body, sidebar, ect. For your layout, I’d suggest it being generally structured like this (these are divs, btw):
[wrapper]
[header][subhead within the header for the dynamic date at the top and rss & cpanel links]
[nav]
[body, though technically “content” would be more appropriate]
[sidebar]
[footer]
[/wrapper]
That little nav section could be a bit tricky depending on how you get those links in there. Alternatively, you could try having that “subhead” section be outside the main “header” div. Something I would recommend doing if you know some about PHP, but not that much, is to take a couple free themes out there and break them apart. You can collect different php files for your structure and edit your one index.php file to accommodate the modified set of files. You can tweak it to get it in the order you want and use CSS from there.
I find this a la carte site design to be kinda fun and a nice shortcut. Also gets your feet wet in the php world. Just make sure you work with copies so if something goes wrong and you can’t fix it, all is not lost. Perhaps it is not the most professional way to get your site made, but it’s nicer than having to pay for someone else to do it, or settling on something you don’t like. Depending on where you got the various themes from, you may wish to consider giving credit to the people whose themes you used. Also, if you get really ambitious, there are several ways to get fonts to display that aren’t safe system fonts. There’s a php method (which I am not familiar with) and then there’s a method using flash and java, sIFR (see it here.) It is something to look into, however you may want to hold off on that for now and just work on getting your php going. Good luck!