Thanks to aliases, watermarking becomes straight-forward.
To apply a watermark overlay to all images within one of your aliases, you can go to the edit screen for your alias,
then go to the Watermark section and paste/type the url of a valid PNG image.
| Field | Description | 
|---|---|
| Image | URL to the pngto overlay as watermark | 
| Scale Percentage | Slider you can set between 20-100 to apply scaling to the watermark | 
| Tiled | Toggle to specify if the watermark should repeat over the images, or just print once | 
| Position | In case of a non-tiled configuration, this field allows you to place the watermark at a predefined snapping point | 
A watermark can tile over your images like:

The settings are:
| Field | Value | 
|---|---|
| Image | https://cdn.ixmage.com/v2/grappler/images/demo/watermarks/wmark-01.png | 
| Scale Percentage | 50 | 
| Tiled | Yes | 
| Position | (not required) | 
And for the non-tiled option:

The settings are:
| Field | Value | 
|---|---|
| Image | https://cdn.ixmage.com/v2/grappler/images/demo/watermarks/wmark-01.png | 
| Scale Percentage | 100 | 
| Tiled | No | 
| Position | Center | 
The image used is a png that has a 50% transparency.
You can read more about watermarks here.