Arras WordPress Theme

In attempt to reduce load on my server, and to increase page views, I'd like to split photo heavy/lengthy posts into multiple "pages". I found an article about how to do this, using the HTML editor of posts, but it doesn't to be doing anything. In a nutshell, it basically says you just have to add <!––nextpage––> and it should automagically split the post at that point, creating a pagination GUI.

It indicates that I may need to change some code " in your single.php loop" if it doesn't work with my theme. Sadly, I'm not 'that' savvy about how to do something like this, and am hoping that either there's a quick-fix, or possibly I'm doing it wrong just adding the <!––nextpage––> code in between paragraphs. Otherwise, maybe some easy step by steps from the wp-admin screen on how to add the necessary code, without risk of goofing up my theme.

Any help would be greatly appreciated! I think this is a really beneficial tool for anyone using this theme! Thanks in advance!!
ps. I'd like to be able to do this without adding another widget if possible.

This is the original article I found:
http://www.wpbeginner.com/wp-tutorials/how-to-split-wordpress-posts-into-multiple-pages/