Go to
http://gallery.sourceforge.net to get info on where to download netpbm. Download the files you need for your OS. If you use linux you have to ask someone else how to make the file work. If you have windows download the binaries and place the folder somewhere (on the hard drive of the server) and remember the path to it. Run config again and inter the path to the folder. There should be 12 .exe files and 4 dll files in your netpbm folder. That is what gallery looks for. I hope this helps.