How to: Image over another image [perfect match]

Hi guys,

I’ve got a simple problem but I cannot find a right solution…

I’ve got two images and I want to put one image (let’s call it: A) over the other one (let’s call it: B).
A and B have got the same dimensions and resolution.

Firstly, I change the white background color of A as transparent color (Image --> Palette --> Set Palette Transparency…).
Then, I select the A image (Selections --> All) and I copy it (Edit --> Copy).
Now, I open image B and I paste A over it (Edit --> Paste --> Paste as Transparent Selection). Here there is the problem! Because of when I have to place the A image I cannot place it exactly over B. I mean, I want to place image A with the same alignment of B, like snapping the corner of image A over the same corner of image B.

Please help me.

To place image A over image B, use your Magic Wand to select the area outside of image A. Now go to Selections > Invert. You should now have image A selected and not its background. Now go to Edit > Copy. Now on image B, go to Edit > Paste > As New Selection. Image A will appear in image B and you can move it to align it directly on top of image B. It will, however be on the same layer as imge B.

If you want image A to appear in image B as a new layer, then once you have copied image A, go to Edit > Paste > As New Layer and it will appear centered in image B. If image B isn't centered in its background, then go to the Mover tool (just below the Crop tool) and move it until it's exactly on top of image B.

I cannot use the Magic Wand to select my white area because it's not continuous.
Let's repeat my steps:
1) open image A
2) change the white background color of A as transparent color (Image --> Palette --> Set Palette Transparency…), here the image is converted in a 256 color palette, with a transparency background (no more white!).
3) select the A image (Selections --> All) and I copy it (Edit --> Copy).
4) open image B and I paste A over it (Edit --> Paste --> Paste as New Layer).
4bis) instead of 4), I can open image B, create a new layer, select it, then Edit --> Paste --> Paste Into Selection
5) The result is always the same, I got 2 layer: in one there is image B, in the second one there is image A, but without the transparency background! So Image A cover image B and I cannot see Image B!

How can I do?