Before you start fixing up the other 3 corners, click on the Eraser tool. Use the settings below. Carefully touch up the ends where the center piece of the corner meets the left side and the top so that it blends. The center piece of the corner should be arranged as the top layer. Turn off all layers except your 3 new corner layers. Right click and choose Merge Visible in the Layer Palette by right clicking on one of the corner layers.
Now you are ready to start getting dizzy?
Here is the dizzy part.
Ok, so you've turned all your layers back on. Copy that left corner. Paste it as a New Layer. Mirror. Move it over to the right top corner. Copy that layer and then Paste as a New Layer. Flip it. Move it down to the bottom right corner. Copy that layer and then Paste as a New Layer. Mirror it. Move it over to the bottom left corner.
Your layer palette should look like this,
the arrangment of layers that is.
Go back to the first page to read some of the things I did with this finished pillow to make all the pillows you saw in the entrance page. It's right below the title for Making Pillows on page 1 of this tutorial.