Login page with MS SQL for C#

Question

Dear all, i want to create a login page for my ppc application in C#. basically, i wll link the login page to SQL server for username and password verification. so i want to know how we write the code to verify the password at SQL server asuming my server name is "tech" and my database is "password" so we should have somethign like this sqlConnection = new SqlConnection; Data Source="tech", Initial Catalog="password"; but the thing is, how to verify the password ??? Thanks all !