Recently, I formatted an external hard drive and I created several partitions on it. For doing so, I used to very good tools:
Both tools are intuitive and makes your live really easy. You can also find good tutorials on line (e.g. looks at this answer on for a step by step GParted tutorial). I’ve just realized that GParted is actually the GUI for GNU Parted that will try next time I want to partition an hard drive (I’ve spotted this tuto 😄).