User Button not working in BeagleBoard C3

Hello,

I want to blink led on pressing user button,as mentioned on the following site.

http://stackoverflow.com/questions/20060047/custom-interrupt-handler-for-user-button-on-beagleboard

I am using Beagleboard-C3 with Ubuntu12.04, I am not able to handle interrupt.

also I want to confirm the pin number of user button in Beagleboard C3