How to add background color on blog? Which class to use and to which file?

Here is an link of blog: http://test1.innovationmindcenter.com/blog

I need to create white background, this black color comes from the template and I need to be able to add white color in order for this blog to looks nice.

I also went over following link: https://stackideas.com/docs/easyblog/administrators/customizations/template-overriding
but that did not help.

Added FTP info and for admin of the website.

Please help.

Thank you