How to partition USB drive for Ubuntu installation?

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http://askubuntu.com – I am not a computer savvy and need to know how to partition my USB drive without messing up my laptop. I already have the boot order set up properly and the USB drive already has the ISO image downloaded onto it. I am ready for install but just do not know how to partition. I am installing Ubuntu 12.4 LTS onto a USB. Can someone help me? I need an easy walk through please. (HowTos)