Login to your blogger account, go to the template and then click on Edit HTML, In Edit HTML you can see your template code and CSS in this Edit HTML section you can change your CSS.
It depends on your template and its HTML structure. CSS calls on the HTML element to style or format it. Different templates have different HTML element names. I would need to see your blog to give you a accurate answer.
I rescued from the site’s archives. It has vibrant red colors, which are nicely offset by the very clean appearance. I’m sure it will be a very good layout for a lot of sites. thanks for sharing the information.