Like this:

package Test;

sub run {
  while(<DATA>) {
    print "$_\n";
  }
}
1;

__DATA__
1
[download]

I made two changes to your code. First, the file handle is always DATA, not PackageName::DATA. Second, I made the package return true, so that you can use it.

If you want to see some real-world examples, then check out these tests (and the modules under t/lib that they use) or Number::Phone::UK::Data