It its default state Origin is a really simple WordPress theme and if you have some previous WordPress experience you shouldn’t have any trouble using it for your own site.
First, if you haven’t done this before, you may want to read How to Install the Theme.
If you are installing the theme on a site with already existing content (like posts), you probably need to recreate all image thumbnails! Otherwise they won’t be displayed with the correct sizes on the new theme. The good news is that you don’t need to do it manually – there are plugins that can do the job for you. A good one is Regenerate Thumbnails. Just run it AFTER installing and activating the new theme and wait till it completes its job.
Origin supports most of the standard WordPress functionality and for the most part behaves the way you’d expect. There are a few intricacies, like the way the tagline and sticky posts are presented, but there shouldn’t be anything confusing and if you’ve ever used WordPress before, you wouldn’t have any problems.
You can get familiar with the Best Practices for Theme Customization here.
If you decide to customize Origin in a child theme (as you should!), it’s best to use the pre-made blank child theme – available on the Origin page. Simply install it just like you did with the Origin theme, make it the Active theme for your site, and then edit/develop it to your liking…