Spoke replacement for Decathlon B'Twin Triban 3

kenan

Evening all, found a broken spoke on my back wheel when I got home from my commute. I happy to try to change the spoke but I haven't a clue what size/guage I need. Can you help me find a replacement please, also do I need a new nipple?

Link to the bike but no real info on their website: http://www.btwin.com/en/sport-road-bike ... #tabs_link

Thanks