Semplice ships with a pre-defined blog template which you can customize and style as you wish.
Styling the blog page
To get to the blog customization area, navigate to Customize > Blog in Semplice. Here you can set things such as typography, the column width of your content, and what navigations you'd like to have show for this page.
Changing the default blog page layout
Currently, there is not a way to modify the pre-defined layout of the blogroll page. You can check out this 'hack' article, however, if you wish to display blog posts in a regular page in Semplice and create your own grid.