Confirmation message box in webapplication

Question

Am using the below message box in asp.net web application. Now i want to convert this message box as a confirmation message box and do something when it is true else means r

Answer 1

ScriptManager.RegisterStartupScript(page,this.GetType(), "temp","javascript:calopen();
",true);

function calopen()    
{    
    if (confirm("Are you sure?"+'\n'+"Are you want to delete"))    
    {   
        enter code here    
    }
    else   
    {   
        return false;
    }    
}