Pretty simple. Read about the Adafruit Neopixel library to send the 18 bytes of data needed to set the color.
6 LEDs x 3 bytes/LED = 18 bytes.
Wire up a button to connect a pin to Gnd when pressed.
In your code set up the pin with its internal pullup resistor.
After sketch start, continually read the pin, it will read HIGH until the button is pressed.
When pressed (reads LOW), send out the 18 bytes and delay for 1000mS x 60 sec/min x 30 min, and send out 18 bytes of 0s to turn off the LEDs.
Go back to reading the button.