open FILE_LIST, "list.txt";
while(<FILE_LIST>) {
 #read each line into the array here -- gotta look up the syntax
}
close FILE_LIST;

##</code><code>##

foreach $filename (@files2change) {
 my $backup = $filename . '.bak';
 rename($filename, $backup)
 open OLD_FILE, $backup;
 open NEW_FILE, ">>$filename;
 while(<OLD_FILE>) {
  print NEW_FILE s/foo/bar/g;
 }
 close OLD_FILE;
 close NEW_FILE;
}