I'm trying to paste one image into another and have them blend seemlessly together. I've tried to make the background transparent but it never seems to work for me. I've also tried selecting just the part I want with the magic wand (assuming it actually selects what I want, which is rare) and then trying to paste just that into the new image. No go.

I have a dog image and a dog house image. The dog needs to seem like he's in the doghouse, but the darn white background keep getting in the way.

What am I doing wrong?