Blog Posts Background Header img size

Hey guys here is my website -> https://www.tannerfresh.com I’m in the middle of customizing it. I need help with the blog posts, I’m wondering why their background is invisible and how to make them the same colour as the home widgets and even better if each blog post could have its own frame instead of a big long continuous one. Where can I set how many blog post appear on the homepage with a “View More Posts” linking to the rest of my posts. And also my header logo size how to keep it at the size it is in google chrome right now, because when I open my page in firefox the header logo is way too big! So Sorry for all the questions just been trying and struggling and thought I should ask ’em all at once, the theme I’m using is the WP Responsive theme.

Thanks in advance
Tanner