If your employees can't see their own information or can't make requests for holidays/absence, it's most likely a problem with permissions. When you setup a user with a login, remember to set the permissions on their account to denote what they can and can't see. The standard setting for an employee is that they "have access to their own HR record" in the HR permissions.
To correct this, log in as an administrator and click on the "Employees" option on the main menu. Then, navigate to the employee you wish to view and, when you reach the employee dashboard, open the employee menu by clicking on the arrow at the top of the page. Select "Edit" from the large drop down menu that appears and scroll down to the bottom of the form to view the permissions. Make sure the employee has permissions to view their own account and click "Update" to store the changes.
The employee will now be able to view their details when they log in to SMB.