What to Wear: Wedding

My wedding dress, July 2013 
On January we´re going to our first winter wedding!  We´re so exited to celebrate this day with them but the main question keeps hunting me, what should I wear to a winter wedding? Is it long dress? What kind of shoes? What kind of dress? What kind of coat? I´m totally clueless, anyone who has a clue? Or just some inspiration? Anyone?