Learn to make your own transparent images, or just cut images out in general.

Start out with the image you want to extract. I'll be using Naruto:
Crop it out and save as a .psd file.

Find the Polygonal Lasso Tool (beside the Magic Wand) and zoom into your image. I like to zoom in around 300-500%, because I can see my image better that way.
Make a new layer below the image you will be extracting, and fill it with black.

Now, go to the layer that contains your image and start making cutting out the image by using the diagonal lines. Once you've cut out a bit of your image, delete the selection.

The black background helps because you can see if there are any parts you missed to extract, so your image will look better.
Keep doing the step above until you've got your image transparent. Remove any parts that stick out, and when you feel you have your image cut out well enough remove the black background and save in .png format!

Note: Don't expect to get the hang of extracting right away. Heck, it took me three days just to extract one part of an image descently! Keep trying and eventually, you'll get it.