how to configure auto fail over

i want to configure auto fail over on router board rbs750.

i have two internet connection
(1) at eth1 , ip address 210.56.16.85 and gateway 210.56.16.81
(2) at eth2, ip address 125.209.76.141 and gateway 125.209.76.242
Local users are connected to router via eth3, my local network is 192.168.10.0/24 and routers local ip is 192.168.10.250

Kindly guide me how to configure that when one internet connection goes down the other backups it and vice versa.

this is my first post at this forum and would be very grateful to you if you guide me.

Thanks & Regards.

Simple Fail over :
/ip route add gateway=210.56.16.81 check-gateway=ping
/ip route add gateway=125.209.76.242 distance=2

just follow the link:
http://wiki.mikrotik.com/wiki/Two_gateways_failover

and you also have to use NETWATCH TOOL to get back to your main connection once its active again.
from your username i guess you are from Indonesia (like me), so i will put a link in Indonesian language.

http://mikrotikindo.blogspot.co.id/2014/05/tutorial-failover-2-koneksi-internet-di.html

Regards
Azfar Hameed Khan

it is very simple.
let me attach a link.

http://wiki.mikrotik.com/wiki/Two_gateways_failover

if you still need help, whats app me at +62 813 1749 3615
we will arrange a teamviewer session.
regarsd