How do I create thumbnails?

You’ll need to set thumbnail images for each post. You can find that in the post edit screen under Featured Image – Set Featured Image. More info on post thumbnails here: https://codex.www.ads-software.com/Post_Thumbnails

Is there a way to get it to grab the first image in the post for the thumbnail rather than have to load the featured image separately?

Thanks.

@willdela, currently no, you have to explicitly set a featured image for each post. You might be lucky enough to find a plugin that would automatically set featured posts based on images within the post.