Tips for Designing within an existing template?

Hello. I have a website here: http://www.nedyken.com . Each page is an individual html. It’s a pain in the butt to update. I’d like to implement wordpress, but redesigning the whole page from scratch is not a possibility. I simply need the wordpress text (blog title, date, content, comments) to split out in the middle of that large white box (instead of writing my updates manually with basic html code).

I had SOME success earlier by modifying the classic template. I took the code in the index.php and basically pasted it in the part of my page where that White box shows info. I then tried to modify the style.css sheet the best I could. It came out so-so, but my problem was that for some reason the fonts appeared drastically larger in IE than in Firefox. Any suggestions on how I can easily accomplish this?