As i said . I am new bie to webserver Programming
So what? It isn't rocket science to look at the code you posted and figure out what part(s) deal with GET requests. The class names provide a pretty good clue, particularly if you know what a client does (asks for information) and what a server does (provides information).
Once you have an idea what part of the code deals with the client request, you can add a Serial.print() statement to see WHAT the client is asking for.
It wouldn't hurt to post a picture of the web page you are serving now, and explain how the user is supposed to change latitude and/or longitude.
It would also be good to look through the html you are sending, to make sure that all close tags follow the corresponding open tag (yours do not), and that all open tags have matching close tags.