Adjusting text width for posts

Hi guys,

I would like to hack my site slightly and even up the white space width on each new blog. My blog is here: https://www.vaguedirection.com/blog.

My theme’s support has said they don’t cover this and have asked me to hire a developer to make some CSS changes, but I like to learn these kind of things so would like to give it a shot.

I am trying to increase the amount of white space on the right hand side of each post so it is symmetrical with the left. Here’s a photo to demonstrate what I mean: https://www.vaguedirection.com/wp-content/uploads/2014/05/blog_outline.jpg

Could anyone advise what code I should be adding / changing?

Many, many thanks!
Dave