Hi,
Welcome to the forum.
Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html
Yes it is possible, but how you do it depends on the type of board, there are many relay PCBs produced for Arduino and they all do not look or are controlled the same way.
Can you post a link to specs/data and or where you purchased the relay PCB?
Thanks .. Tom... 