Pinout for an SMA Connector
First, the spec sheet and mechanical drawing for the connector are linked to directly from the page you linked to above.  The pinout is very clear from that.  Did you look at it at all?  The center pin is the center connection, and the other pins connect to the outside of the coax.  The drawings seem quite clear about this.

Second, that schematic shows 3 connections to the antenna.  if that's what you really want, you can't use a SMA connector since it only has two connections.  SMA is for coax, not balanced line.