Check examples in manual:
https://wiki.mikrotik.com/wiki/Manual:Interface/Bridge#Bridge_VLAN_Filtering
They are simple and relatively easy to understand. Or there’s also this popular thread:
http://forum.mikrotik.com/t/using-routeros-to-vlan-your-network/126489/1
IMHO the most confusing part is that bridge interface can be two things at once. First is interface for configuring the switch (either hardware or software), but also the bridge interface itself can be used as member port of selected vlan (depending on bridge’s pvid).