Blogger

Blogger's Template Designer allows you to customize almost any aspect of your blog's appearance through the use of cascading style sheets(CSS). To add custom CSS snippets to your template, simply open the Template Designer and add your code to the field located in theAdvanced | Add CSS tab. Changes you make will reflect instantly in a live preview beneath the editor.
Note: Editing CSS allows you to change the look and feel of your blog. For changes to the actual content of your blog, including the adding of gadgets or changes to the layout, please use the Edit HTML field located in the Layouts tab. Also remember that, like other customizations, your CSS will be removed if you change designs.
While CSS allows for an almost unlimited number of style customizations, here we'll just go over a couple of the most popular CSS tweaks so you can get a sense of how these changes can be made. For a more comprehensive list of various CSS tweaks, please see the 'What can I do with CSS' article in our Help Center.
The first CSS change we'll go over is how to center the header text on your blog. Head over to the CSS field located in the Advanced | Add CSStab in the Template Designer. Once there, simply drop in the following lines of code: