Creating Password Protected Sign In System In Excel With VBA

I am trying to create simple password protected system in excel. What I have already done is I have a worksheet, which is not visible that holds all user names, passwords and user roles, such as admin and user. Now my problem, I need to create a UserForm that will prompt user to input their details prior to using the workbook. I have no problems with creating the form itself but I cannot really create a code to handle the task. Also, there will be only one system admin, which means that only admin should be able to create users, so that when admin will sign in, he should be able to see the button on the home screen, something like "Create New User". I cannot post my workbook because of the Corporate Copyrights and privacy, but what I can do is post all named ranges that contain password, usernames etc.