To control file size and file name in server write below code in event while saving
IF FileUploadControl.PostedFile.ContentLength < 1024
Dim strserverpath as string
Dim strfilename as string
strserverpath = ""
strfilename = Path.GetFileName(FileUploadControl.FileName)
strfilename = strserverpath & strfilename
FileUploadControl.SaveAs(strfilename)
END IF