creating a new file
 

how would i create a new file?

What kind of file... ?

i want to create a new gif file from another but just smaller(thumbnail)

Then why didn't you say ;). There's lots of inforation available about this online, search on google for things like 'PHP Thumbnailing', and you'll find lots of scripts to do it for you.

check out http://us2.php.net/manual/en/ref.image.php with reference to these functions. You're going to have to read the source image's size with something like getimagesize() and then use the ratio of those dimensions to create your new dimensions.

imagecreatetruecolor
ImageCreateFromGif
ImageCopyResampled
imagegif

check the fetch_thumbnail_from_image function within vbulletin.