Open your green-screened wedding photo in an image-editing program.
Click on the "Layers" window. If necesarry, unlock the first layer by clicking twice on the icon of a lock.
Add a new layer to the image by clicking on the "Add Layer" button.
Click on the "Select" or wand tool from the toolbox. Click on the "Color Range" option, then the eyedropper tool. Click on the green area of the image to select all of the green.
Press the "Delete" key on your keyboard to remove the area.
Click on the "New Layer" button.
Click on the "Import" or "File" menu and scroll to "New" or "New Image." Select the file that contains the background you wish to use, and press "OK."
Press the "Arrow" or "Move" tool and click on the background. Drag the background into place and re-order the layers, if necessary. Click on the layer that contains the couple and drag it upwards.