connect two volume
 

Hello everyone
I quite beginner in using Gambit i don't know how to connect two volumes in order the flow pass through , I created two volume, one is a brick and another one is cylinder,
the cylinder suppose to be connected to the brick and flow go through the brick, i have tried using the subtract and merge.. but i have face an error that the volumes not connected

I really appreciate your time

Hi
please send a simple plan of your model to me to learn you how to do it step by step