To create a connection between the tables you need to:
- open the tables folder from the navigation menu
- click on the Keys link
- click on this icon 
You will then open, the form to create the key (see below).
At this point you need to:
- enter the name of the Foreign Key;
- select the Primary Key table;
- select the Primary Key column or columns;
- select the Foreign Key table;
- select the Foreign Key column or columns;
- click on the Create button
N.B. It is possible to click on this icon 
from the key list to set or edit the Primary Key of the table.