You might wanna talk to God, maybe you'll get him to do it for you.
Other than that, you might wanna start reading on Database design
], while avoiding common DB design mistakes
] (which I don't fully agree with, but it's ok on the whole).
And if you want to design it in a GUI interface, well, there's a few solutions that may actually help, but SQL Server Management Studio comes to mind first (you did specify SQL-Server).