You had received a download link when you had bought the software. Click on it. If you do not have it anymore,
go here to retrieve the link
If the link is valid, you just have to download the new ISO. If the link is no more valid (more than 180 days), then you have to reactivate the link (cost less than $5).
Once you have the ISO, burn it on a CD. Either on your server, or on any other PC, boot from the CD with the USB flash drive attached to the same computer, hit
i for install, verify the destination disk, change if necessary, choose update NL on your flash drive. Power off the PC. Put the flash drive on your server and boot.
VoilĂ
