There are two ways to configure switches in the MT world.
This is the reference for the vlan filtering method
http://forum.mikrotik.com/t/using-routeros-to-vlan-your-network/126489/1
This is another way to make use of switch chips but to complex for me, however it may make sense depending upon your unit.
https://www.youtube.com/watch?v=Rj9aPoyZOPo