This isn't a real answer (It's a quick and careless answer at best, so don't take it too seriously)
But I just thought I'd mention that the the W3C markup validator might be useful to you if you don't already know about it.. It catches bad markup practices or errors on your page and can give you more information on how to fix them. At the time of writing, your front page alone has 10 errors and 3 warnings on it. Maybe this could point you in the right direction?
upon a quick skim of your page you don't seem to be utilising CSS properly. That is to say, that I see you are using css but you have elements on your page (use of <center>
HTML tags, inline styling and things like that) that go against the grain of why CSS was invented.
If you haven't already seen the CSS zen garden, take a quick read/look at it. It should set you right on why we use CSS instead of tables and alignment tags.
(People sometimes don't get this immediately, but , click the links on the right in the zen garden. The same HTML and page content are completely restyled using one html file and seperate CSS sheets)
Good luck!
Edit:
Oh, I almost forgot to mention that internet explorer 8 doesn't have much (if at all) HTML5 compatibility. If you want to develop websites and web apps in HTML5 you'll be hard pressed to serve your I.E 8 visitors and may end up spending more time fixing bugs than you are developing the content.
Some developers are already boycotting I.E 8 entirely to usher in the new era of the web with HTML5 and CSS 3. There are a few js compatibility libraries out there (like excanvas for the new <canvas>
element for example) but they don't work flawlessly and you will eventually have to draw the line somewhere. (lol. canvas.. draw line.. get it?) That being said, i did find this article and this may be useful to you:
turn-on-html5-in-ie8-or-lower
Not every website requires HTML5 and it's new technologies, but if you plan on using it for things like the <canvas>
tag, Id suggest (from my own personal opinion) you forget about I.E 8 and concentrate on browsers that utilise it.
Remember that you can make checks in your HTML to see what browser version your visitor is using.
You can see if they are using an incompatible browser, and if so, you can then alert them that their software is out of date and suggest to them alternatives (such as chrome or firefox)
There's a bunch of tutorials on-line about this, here's the first decent looking one I found in a quick Google search this article covers using this technique for seperate CSS sheets but there are others that talk about the problem I mentioned in more depth and I'm sure you can probably figure out how to do it anyway once you read the article.
Either way, I'd say you've got a little bit of reading ahead of you to understand why your humble website does not work in an increasingly obsolete browser.
Again, good luck to you in your future endeavours.