how to send different subnet traffic to different wan

According to the above diagram, i want to send the traffic that come from LAN1 through WAN1 and the traffic that come from LAN2 through WAN2 on one routeros, how i can achieve the end result?..any idea.

thanks in advance!

Look at the wiki, this is explained multiple times with the use of mangle rules

syadnom, can you point me towards a specific post on wiki or somewhere else?

You have to do policy based routing via the mangle table

Have a look at these links as a guideline

http://wiki.mikrotik.com/wiki/Policy_Base_Routing
http://wiki.mikrotik.com/wiki/Load_Balancing_over_Multiple_Gateways
http://forum.mikrotik.com/t/policy-based-routing-using-two-uplinks/51312/1

I am able to solve this problem, if someone need help regarding this issue, please feel free to ask me.