As always, it starts with opening Lightroom and choosing an image to work with. Click Cmd Shift E to export the image. This screen appears:
Check the checkbox and click on the blue arrows:
Then: click on Edit Watermarks:
Now you'll get this new screen with lots of possibilities:
Like choosing your letter type and size. With the watermark effects you get to choose the location on the image where the watermark should appear.
When you're satisfied with your newly created watermark you'll want to save it. Before actually saving it, choose ´Save Current Settings as New Preset and give your watermark a name. Then click on Create and Done.
The new watermark now appears in the dropdown list as an option for watermarks in your images..
By clicking on the blue arrows behind the watermark you can choose edit. Now you can edit, rename or even delete it.
So there you have it. Seems easy enough right, to create your very own watermark. I have to admit that we're using more and more metadata in our images instead of a watermark. But that's a subject for yet another post.