This is not real, it's just a project i'm working on

I've created a Hotel Management system in C# WindowsForm, it allows staff members to Add/Edit/Update Rooms,Reservation and Customers etc.

Along side this Windows-form i'm creating an ASP.net WebSite where customers should be able to register and reserve rooms online. I've come to the point where i need to create some-type of membership method for this website which should correspond to the membership of the windows form. However i'm not sure what method of membership would be best suited for this, i have looked into the asp.net membership, it's what i want however it creates it's own schema and i don't know how i can relate the information to my customers table and c#windows form.

I would ideally like it to resemble a real-life situation as much as possible anyway, am i going about this the wrong way? in terms of the c# windows-form what other technology would a business use to manage a system like this where they can add/edit/update there system and have a website which relates.

What are my options here?