[1] Blog Style: You can select Grid or List Style. Here we choose style Grid for Blog Page
[2] Sidebar Blog Layout: You can select Right / Left sidebar or full page (without sidebar). And when you select Right / Left sidebar, you are able to choose sidebar in [3]
[3] Blog Sidebar: There are some availabe Blog Sidebars that you can choose. And to design these sidebars, please negative to Appearance > Widgets
Here you can see the complete widgets when you choose Blog Sidebar [3] is Widgets Area
