you first got to render the image...i'll give you one example:
your render looks something like this:
it has the white bacground. Add transparent layer to the image add get rid of the white BG. For futher details just read the rendering part in the tut.
This is what your render should look like...
click on the images to see the difference. I hope that helps you.
your render looks something like this:
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This is what your render should look like...
You must be registered for see images
click on the images to see the difference. I hope that helps you.