You'll require a few things to build your kit. Most of these you'll likely already have. If you don't already have them, they're all very useful so now is the time to pick them up.
An A to B USB cable. You'll need a USB A to B USB cable. These are commonly known as full-size USB cables, peripheral cables, or printer cables.
A 7 to 20 Volt DC Power Adapter with 2.1mm or 2.5mm Center-Positive connector. You can use either the USB connection or a power adapter to power the Freeduino.