Confusion About Reference Field

I have two datasets… Members and Cars. The members primary field is email_address. Members OWN cars. The cars primary field is dash#. Using wix code I want to be able to query the Cars database for cars located in a given state. The state field is in the Members dataset. I have read the docs about songs and artists but I can’t seem to make the correlation?

Please explain and give me the steps to do this.