Originally Posted by
ray_parkhurst
Open the two files you want to use for the overlay
Select the secondary image that will overlay on the other
Perform Layers-->Flip Vertical
Perform Edit-->Select All
Perform Edit-->Copy
Select the primary image
Perform Edit-->Paste into new layer
Select Layers-->Layer Properties
Adjust Opacity to your liking
If the overlay needs position adjustment:
-Select the layer it is in
-Click on the image and move it to correct placement
If the overlay needs rotation:
- Select the layer it is in
- Select Layers-->Rotate/Zoom
- Rotate until it is in correct orientation
Iterate position and rotation adjustments until both are correct
Select File-->Save As
Choose the destination folder
Enter desired file name
Select JPEG in the pulldown menu
Adjust slider to desired Quality level and press OK
Select Flatten
Open saved file and decide if it is OK
If not:
- Select File-->Undo (this will "unflatten" the image)
- Go back and correct whatever you don't like
EDITED TO ADD:
I realized you may have been asking about how to do an animated overlay. If so, let me know and I'll go through the steps.