I wrote it when I was learning how to use symmetric keys, so it should help you.
Click on the Create Database button to create a database with a user table containing a password field. If you get an error when you click on the code, reclick it and it should work the second time.
There are two buttons to populate the table, one via sql and the other using a stored procedure.
There is also two buttons to display the user information. One using the SYMMETRIC KEY, the other not.
Look at the blog link I sent you above for more information on using keys.