Multiwan configuration problem..Help needed!

[bond80]

Hi,

I am a newbie in pfsense. Features are great and very handy to use. I am writing here for helping me a failover configuration issue from expertises here. I could not figure out how i can configure this. My ISP gave to Three IP adresses 1 IP(WAN/REAL) for routed and the other two's are say 192.168.10.15/24(Primary) GW: 192.168.10.254 relates to vlan 10 and  192.168.20.15/24(redundant) GW: 192.168.20.254 relating to vlan 20. I have been using single pfsense box.The problem is how i configure this route this to the WAN IP say X.X.X.85/29. As a whole the scenario is:

|–------>192.168.10.15/24-----------|
                                                            |              (VLAN 10)                        |
    Internet Cloud <------Real/Wan IP--|                                                      |--------> LAN
                                                            |                                                      |
                                                            ---------->192.168.20.15/24----------|
                                                                            (VLAN 20)

Hope you understand the scenario. Now, Please can somesone tell me with step by step configuration process for single pfsense box.
Thanks.