I assume you want to create the datamodel? Do you have a screen shot of your current ERD (table)? That would help.
The way it works in Qlikview is, you may need to rename the key field that you want to join with another table. Once the key fields are the same, it will automatically create the join (It's not the same as in SQL, which you just drag a line from one table to another - you need to do it via Qlikview Script).
Table Employee has 2 fields:
Table Department has 3 fields: (Just for our test purpose, ignore how "Emp Number" is created in Department table )
Emp Number, DepartmentID, DepartmentName
To join the Employee and Department via EmpID or Emp Number as the key, you need to rename either one to match one another. So either you need to rename Emp Number to become EmpID (or vice Versa).