How can I use the ClassMap to connect 2 classes?

[Mihai-Aioanei]

Hello!
If i have 2 csv files (2 classes: user and department which has a list of users) that look like this:


how can I use the ClassMap (references) to write users like:

and when i read them to add users to lists in departments. Thank you!

btw now i have something like this: