<?php
# If you don't know the type of image you are using as your originals.
$image = imagecreatefromstring(file_get_contents($your_original_image));
$frame = imagecreatefromstring(file_get_contents($your_frame_image));
# If you know your originals are of type PNG.
$image = imagecreatefrompng($your_original_image);
$frame = imagecreatefrompng($your_frame_image);
imagecopymerge($image, $frame, 0, 0, 0, 0, 50, 50, 100);
# Save the image to a file
imagepng($image, '/path/to/save/image.png');
# Output straight to the browser.
imagepng($image);
?>