To center the site title in the Blaskan theme, you can add CSS like this to your Appearance → Custom Design → CSS page:
I found what selector to use by using the web inspector tool in Chrome. I right-clicked on the title and selected the "Inspect Element" option. When you do that in some browsers, it will show you the HTML code for what you clicked on as well as all the CSS that applies to that element. In some browsers, you can get install an add-on to get the same function, such as Firebug for Firefox. I would highly recommend checking up on how the web inspector works in your browser—it's a really handy tool!