Attachment from external URL

Hi! I want upload some pictures from an array, and attach images to posts in orchid panel.

foreach ($movies as $m) {
$post = new Post; 
$post->title =  $m['title'];
$post->description =  $m['desc'];
$post->save();

foreach ($m['img'] as $g) {			 
$post->attachment()->syncWithoutDetaching($g);
}
}

I try

		$file = new File(file_get_contents($g);

		$attachment = $file->load();		 

			$post->attachment()->syncWithoutDetaching(
				$attachment
			);

and $post->attachment()->syncWithoutDetaching( file_get_contents($attachment) );

But I got error like "Argument 1 passed to Orchid\Attachment\File::__construct() must be an instance of Illuminate\Http\UploadedFile, string given, called in"

Of coure $g is an url like "http://etc.etc/etc.jpg" is string, but when I use file_get_contents still string but image code �
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But I don't know how to get int from a picture, I want attach for Post model. Thanks if someone can help me