How to bind data to ReportViewer

Question

I am able to connect a ReportViewer into my rep.aspx page that generate report of a database table named finalResult. this table have two field named stdId and subTotal. My ReportViewer show every data of this two field, but I want to filter the data, like only those stdId that have subTotal more than 40. I don't know anything about ReportViewer Please help me.