I notice you've set the page div at 2000px for max width, and if you are planning on inserting 2000px wide images, there are several things you should be aware of.
First, on pages on your site with multiple images, your page loading is going to be very slow. This has a tendency to make the short attention span webbing public click away instead of waiting a long time for the page to load. 2000px wide images, even highly optimized, are going to be up in the 1-2MB range.
Secondly, search engines consider page loading times when calculating search engine ranking and slow loading sites will have their ranking discounted, and in some instances heavily. That means that your site will show up much lower in search results and that will mean less traffic to your site.
Thirdly, on reactive/responsive designed themes, they will automatically resize images on the fly for narrower browser window settings and devices and if someone is viewing what was a 2000px wide image on a smartphone, it is going to lose a lot of clarity and resolution.
Lastly 20% of the webbing public worldwide are still on 1024px wide monitors which means that 2000px wide image will be wasted on them and the percentage of people with monitors over 1400px wide is in the single digits. You are targeting a very, very small audience.
In general I don't recommend anything more than 1000px wide for images and even then those images have to be optimized for the web so that they are kept to around 150-200k maximum file size (100-150k would be even better) and that you set the site so that there aren't too many images on any one page.
All that said, on your "blog" page, you can make the content area the full width by adding this to your CSS.
margin: 0 0 0 20.2128%;