How tp open popup in new tab or new window

place the code below in your code behind file from where you want to get the popup in another window.
//Considering the page PopUpPage.aspx contains the data you want to popup 

string script = "";
        script += "<script language='javascript' type='text/javascript'>";
        script += " var win=window.open('~/PopUpPage.aspx', 'popup','width=802,height=500,directories=no,location=no,menubar=no,resizable=1,scrollbars=1,status=no,toolbar=no');";
        script += "</script>";
        ClientScript.RegisterClientScriptBlock(this.GetType(), "Test", script);