Script to excute Javascripts Alert function in ASP.NET with C#

//Script to excute Javascripts Alert function in ASP.NET with C#
// button_CLick(objects sender,Eventargs e)
// {
// string val=Textbox.text;
// if(val=="Navyanth")
// {
// alert("Navyanth")
// }
// else
// {
// alert("Others")
// }
//
// public void alert(string msg)
// {
// string str = "write script1 langauge equal java script1 " "+" " write alert(' " + msg+" ');";
// RegisterStartupScript("ds",str);
// }

ps: Remove write