Hello and welcome to LQ.
Three common ways to create a linux usb.
One is to use a creator like unetbootin or live usb creator. See www.pendrivelinux.com
Two is to use the distro's suggestion. Some may have you boot to a cd on any system and then use their usb creator.
Three is to simply use to use dd to copy hybrid iso to usb.
There are also network boot and install options too.