code for login in threetier architecture -BAL DAL Presentation layer

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ASP.NET

any one pls help me out how to write code for login page in three tier architecture

i took folders like 1> Utilities : database connections and extra......
2> datacontainer: in this i declare parameters and set get properties like below

private int _loginid;
private string _username;
private String _password;

public int loginid
{
get{return _loginid;}
set {_loginid =Value;}
}

as usual username and password i wrote

3> coming to datalayer i declared object of datacontainer and i write code like below in datalayer

private void NacreLogin(DataContainer objdc, string CmdText)
{
util.Open();
SqlCommand Cmd = new SqlCommand();
Cmd.Parameters.Clear();
Cmd.Connection = util.SqlCon;/*here iam getting SqlCon not accessble due to security level*/
Cmd.CommandType = CommandType.StoredProcedure;
Cmd.CommandText = CmdText;
Cmd.Parameters.Add("@loginid", SqlDbType.Int).Value = objdc.loginid;
Cmd.Parameters.Add("@username", SqlDbType.VarChar).Value = objdc.username;
Cmd.Parameters.Add("@password", SqlDbType.VarChar).Value = objdc.password;
}
My doubts are
how to write code in buisness logic.
when i design and code login.aspx . and enter the values in username,password and loginid for login.what is the process in business logic
how entered values will be compared to database sp_tbl_login storedprocedure values.

Thanks In Advance