there is no in depth how to for the manage relational table behavior.
It is used to manage a linking table.
A linking table is used to create a many to many relationship between two tables.
for example, lets say you have a products table and a categories table and you would like to assign multiple categories to each product, you would need to use a linking table to create the many to many relationship.
The available documentation for the manage relational table behavior is in the help:
Under Features -> Managing Multiple Records -> Manage Relational Table