Add a watermark to picture

Add a Watermark to image.
Añadir una marca de agua a una imagen.

You can use paint to add text to a picture.
Puedes usar paint para agregar un texto a una imágen.

or use some website that will add an image or text as watermark:

http://www.picturetopeople.org/image_utilities/watermark/online_digital_watermark_text.html

or with Microsoft paint that is available under Windows:

else with adobe photoshop adding an invisible layer full of your logo...