Look at the top of the page where the little picture of the connector is. Each connector is labeled (J1, X1, X2 etc). And it should show you where pin #1 is, and gives the pin # for the starting and ending pin on each row in relation to the connector. (NOTE the location/orientation of the connector itself)
So pin #1 is the pin on the TOP row all the way to the RIGHT. Opposite the large primary pin (#73)
