The switches are labeled SW0 to SW7, and are available on the SWITCHES header. The switch hardware is shown below:
When pressing one of the switches, the corresponding SW pin on the SWITCHES header will be pulled low. When the switch is released, the switch's 10k pull-up will pull the line to VTG. The 150 Ohm resistor prevents a large current to flow to ground in case of wrong wiring.
Connect a cable between the SWITCHES header and one of the PORT headers. Use a 10-wire cable to connect to all eight switches or a two-wire cable to connect to one or two switches.
On most Atmel AVR pins configured as input, you can enable an internal pull-up, removing the need for an external pull-up on the push button. In the Atmel STK500 design, an external 10K pull-up is present to give all users a logical '1' on SWn when the push button is not pressed, even if the internal pull-up is not enabled.