Information on adding firewall rules to Pfsense can be found here. Once you have verified internet connectivity you can move on to the next step which is adding blocking rules to all other interfaces except the WAN on your firewall as seen highlighted in the picture below.

Once up-linked, connect to the wireless router via the wireless interface and ensure you have network connectivity to the internet. Once the IP is assigned you will want to up-link your wireless router to the GWN Pfsense interface using a network cable. Now login into your wireless router and assign a static IP to the WAN interface as seen on the picture to the left. NETS_GWN can be replaced with the IP address assigned to the wireless router as described below. Note that under the source column you will see NETS_GWN which is an alias that will hold the IP address of the wireless router. Once that is complete you will want to navigate to Firewall > Rules and assign a base rule on the GWN tab that allows traffic over the interface as seen above. Once the interface is added you will want to edit the interface and assign a static IP and interface name which in this case is 172.16.10.1/24 and GWN (Guest Wireless Network) respectively. The first step in our setup is to login to your firewall and go to interfaces > assign and add an interface as shown highlighted below in the picture.

Information on AP + WDS is available here. This severely limiting factor is our main motivation for using the above setup since nearly every setup we have deployed has been extended using WDS. Note: As of Pfsense 2.1.5, while wireless interfaces are supported, wireless interfaces with AP + WDS are not supported.

Pfsense wifi access point