Step-by-step Installation of Ubuntu Server
 F irst, download the current version of Ubuntu Server .  Currently, it's 1604 LTS (always choose an LTS version). A 64-bit  version is recommended. A 32-bit version is available though.    After downloading the ISO image, you need to create a bootable CD/DVD  or USB flash. If you have already done so, put the disc in your drive,  or insert the USB flash, and reboot your machine. BIOS must be set up to  boot either from the CD/DVD or USB flash depending on which  installation method you choose.       Continue reading here .