stop guessing, its more important to learn.
Read these first. — > https://help.mikrotik.com/docs/display/ROS/Bridge+VLAN+Table
http://forum.mikrotik.com/t/using-routeros-to-vlan-your-network/126489/1
Then look at Para C here - https://forum.mikrotik.com/viewtopic.php?t=182373