hi how to calculate total profit between two dates?

hi in my tblCurrencySale contains csProfit and csDate..so now i want to calculate total profit
like in my aspx page two dropdowns r der its only date..
so now i want to calculate profit between two dates
like 5/18/2012 and 5/30/2012 when i click search should display total profit in text box..can u suggest me how to give sp and call it in aspx.cs page??

thanks