Store Pocedure And Parameter

hello guy...i have a problem with my coding....i have store procedure that already create in mssql server 2005...that store procedure have a parameter....

Store procedure code

 set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go


ALTER PROCEDURE [dbo].[Users_login]
@username varchar(50),
@password varchar(50)
AS
BEGIN
SET NOCOUNT ON;
SELECT User_application_id, User_fname, User_lname, User_last_activity
FROM Users U
WHERE U.User_name = @username AND U.User_password=@password
END this is my asp.net code Dim connLog As New SqlConnection
Dim cmdlog As New SqlCommand
Dim readerLog As SqlDataReader

connLog.ConnectionString = ConfigurationManager.ConnectionStrings("PVMCCon").ToString()
With cmdlog
.CommandType = CommandType.StoredProcedure
.CommandText = "[Users_login]"
.Connection = connLog
.Parameters.Add("@username", SqlDbType.VarChar, 50, userTxt.Text.ToString())
.Parameters.Add("@password", SqlDbType.VarChar, 50, passTxt.Text.ToString())
End With
Try
connLog.Open()
readerLog = cmdlog.ExecuteReader()
If readerLog.HasRows Then
While readerLog.Read
usernameStatusLabel.Text = readerLog("User_fname").ToString() & " " & readerLog("User_lname").ToString()
lastActivityLabel.Text = readerLog("User_last_activity").ToString()
Session("AuthenticatedID") = readerLog("User_application_id").ToString()
End While
PanelLoginSuccess.Visible = True
PanelLoginView.Visible = False
Else
SignInPopupExtender.Show()
End If
Catch ex As Exception
loginStatusLabel.Text = ex.ToString
Finally
connLog.Close()
End Try
End Sub so the problem is...how can using the store procedure that already have a parameter and how i want to set the parameter value in my code?????