Trying to merge images

Okay, I'm trying to create a final image by merging several (quantity will vary) images into one. This is the code I've got, but it's totally non-functional. I know I'm doing something wrong, but I don't know what.

//Define base background image
$base_background = imagecreatefromgif('adr/images/misc/landscape.gif');

//Output background image
$background_image = '';

//Merge
imagecopy($background_image,$base_background,0,0,0,0,1000,839);

//Check if image active
if($mw_image)
{
	$mw_image = imagecreatefromgif('adr/images/buildings/inner_wall_139.gif');
	//Merge images
	imagecopy($base_background,$mw_image,0,0,0,0,1000,839);

}

PHP:

 

Your $background_image is blank, it needs to be an actual image resource, so instead of = '' needs to be something like this.

$background_image = @imagecreatetruecolor(1000, 839) ;
//sets background to black
imagecolorallocate($background_image, 0, 0, 0);

Code (markup):

And you may want to use imagecopymerge and not imagecopy if you're trying to put the base background on top of the $background_image.