configure FortiSwitch124 poe with FortiGate40c

Hello,

  I have fortgate40C unit with fortios 5.3.15 running . Now i have a fortiswitch 124POE which needs to  be connected with this fortigate40c . In my fortigate I am not able to see fortiswitch controller. 

How can i configure fortiswitch and fortigate, so that i can access fortiswitch too from the same lan.