The first thing you will need to do is add the employee as a user in the portal, this is done under the section Users. In this section you click the button Add user. When you have added the employee as a user you can then add the user to an application, this is done under the section Applications. Choose the application you want to add the user to and click the Add user button.
When you have added the user to an application you can decide what you want the user to have access to. You have the option to add the user to a Group and from there automatically get access to the correct server, publishing destination, repositories and permissions. You can also individually add each user to the correct Server and possible Publishing destinations, and after that open up 2c8 Modeling Tool and give the user access to the correct repositories.