Adding new expressions to Blogger templates...
Blogger's template engine is powered by a flexible editing language, consisting of a set of Widget Tags which use expressions to conditionally change the output HTML for each post and page on your blog. Using these expressions, you can customize the HTML output of your blog, to adjust the look and feel. You could, for example, show an image behind the header, but only on the homepage. Or add a flower icon, next to a post's title, if the post has the 'Flower' label. You can customize your blog's template under Settings > Template > Edit HTML.