Create A Relationship
Select the Child table in the Object Browser and press F10 or select Relationships/Foreign Keys from the popup menu or click on the foreign keys subtab in the Create Table tab to create a foreign key.
Select the parent or the Reference Table from the combo box.
Specify the FK name and select the corresponding columns of the current Table. Each cell in the grid will popup the corresponding columns for the table.
If you want to create an FK on multiple columns just select those columns from the dialog box. Also select refrenced database, refrenced table and refrenced columns. After you are done, press Save.
Note: If you want to set rules for On Delete or On Update operations then you can do it from here.