It can be downloaded for free at http://www.irfanview.com/
First is just the card
Next you draw a text box on the picture where you would like the watermark. All you have to do is click on the picture and draw. If you don't like where it is you can Undo the box.
Next you go to the Edit Menu and tell it you want to insert text into the text box. I have highlighted it here.
Then decide what you want the text box to say. Here I am typing in the text. If you want a copyright symbol just click on Append Copyright and it will show up for you automatically. No having to remember codes and using the ctrl button at the same time. Yay for that! As you can see here I have added my text and chosen the font. When you chose the font and font size is when you also may choose a color. I usually use Gray, Silver, or White depending on the card.