Retrieve Stored Procedure

I need some help retrieving the stored procedure listed below.  I would like to use a drop list to select the variable "UserName" and textboxes to send the variables "StartingDate" and "EndingDate".  How do I pass these variables and then have the results show up in a gridview?  Any advice would be greatly appreciated. 

CREATE     PROCEDURE [dbo].[aspnet_starterkits_GetTimeEntryUserReportByUserNameAndDates]
 @UserName NVARCHAR(256),
 @StartingDate           datetime,
 @EndDate          datetime
AS
DECLARE @UserId AS UNIQUEIDENTIFIER
SET NOCOUNT ON

SELECT @UserId=UserId FROM aspnet_users WHERE UserName=@UserName

SELECT
 @UserName as UserName,
 SUM  (timeentryDuration) AS TotalDuration,
SUM  (timeentryOvertime) AS TotalOvertimeHours
FROM
 aspnet_starterkits_TimeEntry
WHERE
 aspnet_starterkits_TimeEntry.TimeEntryUserId=@UserId
 AND
 TimeEntryDate between @StartingDate and @EndDate