How to configure dhcp for interface with relay bridge protocol

Hi, it is first time I use openwrt.
it I use raspberry pi, I do have usb 4g modem(as device usb0 interface wwan, it this device has already dhcp server which gives ip addresses to 150), also I have TPLINK usb wireless adapter as hotspot(interface lan 192.168.10.x)
I want wwan interface give internet to lan interface but it I not know what the configuration to make dhcp to work, it if I connect wifi or lan it they not automatically get ip, but if I manually enter ip for wifi or lan it they get internet.
I followed this tutorial:
interface: usb_bridge, protocol: relay bridge, ip192.168.32.2 (networks lan wwan),
wwan: static ip gtw, dhcp ignore
lan-br: ip dhcp ignore
It when lan or wifi is connected they not get new ip 192.168.32.x .
When I set computer ip to gtw then it this computer is able to access internet (if I want to access openwrt web config or ssh I set computer ip and browse for openwrt web interface)