I've moved my LR catalog to an external - but suddenly there are multiple versions and my photos are either not there or in separate places. I want all catalogs in one Master Catalog. Couldn't follow the tutorial. My file only says "create new folder" there isn't an option to "create a catalog".
You really only need one catalog. With that catalog you can import images from any hard drive connected to your computer. If you have multiple copies of your images and multiple catalogs then you have gotten ahead of yourself without understanding how the Lightroom catalog works. You can create a new catalog by clicking on File/New Catalog. But it would help if you understood what you're trying to accomplish.