Look at the state change detection example in the IDE (File, examples, Digital). You will probably need debounce on the switches, too. Connect the switch between ground and the digital input. Enable the internal pull-up on the digital input (pinMode(pin, INPUT_PULLUP);. Note that the digital input will be LOW when the button is pressed. For hardware debounce, connect a 0.1uf cap across the switch. Hardware debounce like described will debounce most switches (that I have tried).