Dear Elizabeth,
After you create gallery on gallery post type you need to create template then this template you have to choose from gallery post.You can find this option on top right of edit page.
To create template first go to
Appearance -> Template -> Add new template -> select galleries for single post and archive template -> then create gallery on that page.( While creating gallery you can adjust grid or slider layout )
Please go through this tutorial for reference: https://livecomposer.help/article/184-creating-photo-galleries-in-live-composer
Note: As this support is related to plugin, so in future please consult to respective plugin author. They will guide you more properly.
Best Regards