Hi,
if you want to communicate between two vlans then you need a L3 device like a router on a stick or use a multilayer switch and do intervlan routing with SVIs but STP has got nothing to do with it.
STP is for alleviating L2 loops in a L2 network by blocking some ports and forwarding on others.
In STP what you can configure is which switch will be the root bridge and which ports will be forwarding and blocking by manipulating link costs or port priority.
tell us what you want exactly and explain your topology so we can tell you what's best and what to configure.
Regards.
Alain.
Don't forget to rate helpful posts.
