Backlight is not theme-able, nor are its albums embed-friendly. That latter thing meaning that you can’t embed albums into Wordpress pages.
Instead of themes, Backlight has its Designer, which allows you to customize the appearance and behavior of your website with tremendous flexibility, without having to code or hire someone to code a theme.
Our WP Theme add-on takes your settings from within Backlight’s designer – mostly based on your chosen page template – and creates a matching Wordpress theme. You can see this in action on The Turning Gate’s own blog, as well as on other sites that user’s have shared in this forum. The Backlight WP theme is fairly vanilla by intention, to ensure high compatibility with available Wordpress plugins.
If you want Wordpress to be the main thing, then you’ll have to settle for whatever design approximation you can achieve via Backlight’s designer in getting your galleries to match your chosen Wordpress theme. Personally, I dislike Wordpress, so I would generally contest that Wordpress themes are awesome, built as they are on Wordpress itself.
Here’s a video; it’s concurrent with Backlight 1, so much has changed, but the way the Wordpress them works after install is mostly the same.