An Ubuntu installation ISO contains everything that is needed for booting
on old BIOS firmware and on modern EFI firmware. You just need to burn it
as "image" to the DVD, not as "data project" where you could compose a
DVD from more than one file.
If you already have a GNU/Linux system with DVD burner, you may use Xfburn,
K3B, or Brasero which all offer image burning (which you want) and data
project burning (which you don't want).
On the shell command line, it would be
growisofs -dvd-compat -Z /dev/sr0=ubuntu-16.04-server-amd64.iso
xorriso -as cdrecord -v dev=/dev/sr0 blank=as_needed -eject ubuntu-16.04-server-amd64.iso
If you only have a MS-Windows system for burning, then look for instructions
like in https://technet.microsoft.com/en-us/library/dd451080.aspx
You may also put the ISO flatly onto an USB stick. (Again, not as file into
a filesystem but as filesystem image.) For GNU/Linux instructions see
With MS-Windows consider programs "win32diskimager" or "Rufus" in its "dd"
mode (not in its file unpacking mode).