Me too, I love the one with her tongue out.
For the 'high resolution' stuff, maybe this will help. They want a print quality photo, so the print will be a pretty as the pup. If you are using a digital camera, you need to make sure its on the highest quality setting, that will create a picture of high enough resoulution to print (depending on the camera). You can check the dpi in an application like Photoshop. If the picture is real big when you open it to look at it, and the file size is 1-2 MB, then its probably what they need.
If I am confusing the issue, you can send me any picture and I can prep it for print (I manage a Graphic Arts dept for a printing company!) Let me know if I can help. -Bryan