I was disappointed that I can only select dog or cat in the configuration. I also notice the text bubble is being cut off (Dashboard 10.4.8). I can't seem to post a screen shot of the issue. There is also a discrepancy between the default Dashboard weather monitor (Accuweather) and yahoos weather service. As much as 5 degrees at times. DO NOT consider using this widget for making a decision to bring pets inside or to leave them out. I have a automated dog door. :-)
The pictures MUST be on your hard drive. Where you get them is up to you, perhaps downloading them form a digital camera, or maybe somebody emailed you a picture. When you have these on your computer in a location of your choice, just find that location and use the method as I described below and it will work fine.