Add watermark to your uploaded images and customize your watermark appearance on a user friendly settings page.
Please specify debug information like:
Contact your hosting provider and ask them to enable GD extension for your host, because without GD extension you won't be able to watermark your images.
Contact your hosting provider and ask them to install FreeType Library on your host, without it you won't be able to make text watermarks.
No there's no way to watermark previously uploaded images. I plan to implement this feature in Watermark RELOADED Pro.