$filename = "testfile.dat";
$payload = "qwertyuiop";

$args{user} = "xxx";
$args{password} = "yyy";
$host = "s.a.c.u";
$path = "/some/path/".$filename;

print "connecting\n";
$sftp = Net::SFTP->new($host, %args);
print "open\n";
$handle = $sftp->do_open($path, SSH2_FXF_WRITE | SSH2_FXF_CREAT);
print "write\n";
$sftp->do_write($handle, 0, $payload);
print "close\n";
$sftp->do_close($handle);