Note: You can skip directly to the video for a visual guide to the Layout and Template sections of the Blogger platform - the two main sections that define your blog design.
One of the first things a new reader sees in your blog, even before the content, is it's design. The quality of your blog is naively discernible just by the look and feel of it. In order to catch the attention of new visitors to your site, you must up the attractiveness quotient to be at par with your competitors.
The design of your blog in the Blogger platform is defined by the "Layout" and "Template" sections. Layout is an intuitive summary of the blog design and is entirely dependent on the template. Template is the actual code in XML. The arrangement of blog widgets and their appearance can be changed in the Layout section, while smaller details can be edited in the Template section.
The template section also offers the ability to back up your current template or upload a new one. Not that uploading a different template does not affect your blog posts - the content will remain intact and its appearance will adjust according to the new template.
Watch the below video to get an idea of the template and layout sections.