Cisco Router backup isdn

Hi i have 3 interfaces

interface FastEthernet0/0

interface FastEthernet0/1 195.222.58.112 255.255.255.192 ---- wan

interface BRI0/1/0 ---- backup isdn

i make configure but i am not shure how to make rest of configurations please help me with this configuration how to make backup isdn if interface fastethernet 0/1 go down what kind of route i need to set and that stuf tnx

! version 12.4 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname testrouter ! boot-start-marker boot-end-marker ! enable secret 5 $1$CK0h$HnPVxGeULHA.8chXOSEy4. ! no aaa new-model ! resource policy ! mmi polling-interval 60 no mmi auto-configure no mmi pvc mmi snmp-timeout 180 ip subnet-zero ip cef ! ! no ip dhcp use vrf connected ip dhcp excluded-address 192.168.164.0 192.168.164.50 ! ip dhcp pool 192.168.164.0 network 192.168.164.0 255.255.255.0 dns-server 195.222.32.10 195.222.32.20 default-router 192.168.164.10 domain-name xxxxxxxxxxxxx ! ! no ip domain lookup ip domain name procreditbank.ba ! isdn switch-type basic-net3 ! ! ! username testrouter password 0 cisco username r-sa01 password 0 cisco ! ! ! ! ! interface FastEthernet0/0 description Ethernet Konekcija ip address 192.168.164.10 255.255.255.0 ip nat inside ip virtual-reassembly duplex auto speed auto ! interface FastEthernet0/1 description BIHNET LeaseLine Primarni link ip address 195.222.58.112 255.255.255.192 ip nat outside ip virtual-reassembly duplex auto speed auto ! interface Serial0/0/0 no ip address shutdown clock rate 2000000 ! interface BRI0/1/0 no ip address isdn switch-type basic-net3 no cdp enable ! ip classless ip route 0.0.0.0 0.0.0.0 195.222.58.65 ! ip http server no ip http secure-server ip nat inside source list 1 interface FastEthernet0/1 overload ! access-list 1 permit 192.168.164.0 0.0.0.255 access-list 1 deny any ! ! control-plane ! ! line con 0 line aux 0 line vty 0 4 login local transport input telnet ssh ! end