In BWA each navigational entity has to have one fact table and dimension tables around. You can have multiple fact tables but the Explorer GUI can navigate only within one. So the first thing to do in Index Designer is to define the relationships between the tables.
The primary key column from one Dimension is right clicked, and "New Join" is selected.
The Join gets a name...
...and the join attributes are filled out.
Note: A m:n relationship is not yet supported although shown.
With the joins defined the next step is to define the measures.