If your USB drive doesn't show up, reformat it as FAT32. Select an ISO file or a distribution to download, select a target drive (USB Drive or Hard Disk), then reboot once done. It loads distributions either by downloading a ISO (CD image) files for you, or by using an ISO file you've already downloaded. UNetbootin can create a bootable Live USB drive
You can either let UNetbootin download one of the many distributions supported out-of-the-box for you, or supply your own Linux. UNetbootin allows you to create bootable Live USB drives for Ubuntu and other Linux distributions without burning a CD.
