is this kind of drag and drop page layout common nowadays? I feel like I'm going to have to buy you all a beer.
I've got my own webserver, so my inclination is to try to install it there because it's there... it sounds like it might be much more sane to host it elsewhere though? Is there a benefit to something like "webfaction" as suggested elsewhere versus the github hosting? I'd never heard of github hosting websites before, but I definitely trust the brand and definitely like the idea of versioned website updates.
Just keep in mind that while themes from ThemeForest (and similar marketplaces) look great, they are usually a disaster from a code perspective. These should be seen as a temporary measure, and one that will be largely discarded when you have the funds to dedicate to a better site.
Source: I've made quite a bit of money fixing ThemeForest themes when the business outgrows them.
If you already have a web server, it might be a better idea to host your website there. Github Pages is only for static websites, so you can't use it to host websites using WordPress et al. (Since you linked to a WP theme.)
Find some suitable stock photo here: http://www.imcreator.com/free
Upload it here: https://pages.github.com
Professional looking website in a couple of hours.