The USB Boarduino is almost completely assembled. Finishing it up should only take a few minutes.
Check the parts in the bag, you should have the tested USB Boarduino board, a stick of 0.1" header, a 2x3 ISP header, a 28pin socket and a preprogrammed ATmega328p.
Next, you can attach header pins to make the USB Boarduino fit nicely into a breadboard. If you want to solder wires to the pins instead (free-wiring) you should skip this step.
Break the break-away header into four pieces: 4 pin, 6 pin, and two 8 pin.
You can use any version of the IDE, when you plug in the USB boarduino it will show up as COM port (install the FTDI drivers that come with the IDE package if you're running Windows or Mac and have not done it yet).
Select Diecimila/Duemilanove with 328P in the Boards menu!