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.
If you set a post as a “Sticky” it will appear larger at the top of your theme, you can use this to draw attention to important posts.
The tagline is used for the text at the top of the theme, you can set this under “Settings” > “General”.
Origin uses the Customizer, to use this visit “Appearance” -> “Customizer” where you can set the logo, fonts, link color and more options.
If you aren’t completely satisfied with the way Origin looks (and works), I have some good news for you – this theme is actually made to be customized. It’s a parent theme. You can always make your child theme (based on Origin) and change whatever you want.
And if you aren’t quite familiar with the whole “Child Themes” and WordPress theme customization concepts, here is a nice and short tutorial.