Hi @deejay86 ,
Thank you for reaching out to us. To enable the sidebar on blog page, please navigate to Theme Options > Layout and Design then set the Content Layout to Content Left, Sidebar Right or vice versa.
Then navigate to Theme Options > Blog > Layout and set to Use Global Content Layout
Once the sidebar is enabled you can add widgets to your Main Sidebar via Appearance > Widgets. If you don’t want to use the Main Sidebar then you can simply create a new custom sidebar, add widgets in there and assign it to blog posts (see https://theme.co/docs/work-with-unlimited-sidebars)
Now to set the background color or background image, navigate to Theme Options > Layout and Design > Background Options and set the background as you need.
Hope this helps!