VPN IPSEC Site to Site -> DHCP network HQ for network Branch

Hi,

I'm a beginner on the fortinet, so I need some help. I have fortigate 80E in enterprise HQ with DHCP configuring, a 50E fortigate in enterprise branch I created an IPSEC VPN connection between HQ and Branch, I need the 50E fortigate to assign ip to stations originating from the fortigate 80E through the VPN tunnel. Could someone help me?