Ideas:
As other have said push the main content area or the "mat" if you prefer down from the top.
Add padding to your text, its to close to the outside of the "mat" add like a 10px padding all the way around.
Play around with different fonts I don't like the one you are using but that could just be me. Font choice is very important in web design.
In Safari and FireFox the content is centered, but in IE7 it is not it goes over to the left.
Get rid of the underline on your " Welcome To The Japan Karate-Do Federation"
I like the "mat" and the logo, but not that "Japan Karatedo Federation" image, again try some different fonts and this site could look pretty good.
Also put in a doctype, if you don't know what that is then google it and invest 5-10 minutes of your time learning what it is. You are using CSS...good. Use what ever doctype you prefer a lot of zealot bitch asses think you HAVE to use XHTML. I use it just because I'm tired of the bitch ass web designers complaining to me. But in the end they are retarted since 99.999 percent of your users will never look at the HTML code, so who gives a a flying *explicit*