This requires changes in the configuration for your Web Project in Web Designer:
Edit | Configure project | Web project
Located under IT Shop | Employees for whom a request can be placed
Located under Employee | Employees which can be edited by the current user
Located under Employee | Employees authorized to add and edit employees
For each entry, click the "Customized" check box and enter the appropriate SQL condition.
For more information on using Web Designer, please refer to the Web Designer Reference Guide