Calling ASP.Net Page methods using jquery???

A dummy page method :

[WebMethod()]

public static string sayHello()

{

return "hello ";

}   

Please note that page methods must be declared as static, meaning a page method is completely self-contained, and no page controls are accessible through the page method.

Calling a page method from jQuery:

<script type="text/javascript">

$(document).ready(function() {

$.ajax({

type: "POST",

url: "pagemethod.aspx/sayHello",

contentType: "application/json; charset=utf-8",

data: "{}",

dataType: "json",

success: AjaxSucceeded,

error: AjaxFailed

});

});

function AjaxSucceeded(result) {

alert(result.d);

}

function AjaxFailed(result) {

alert(result.status + ' ' + result.statusText);

} 

</script>   

Mange Form authentication and authorization using web config file??

Following code demonstrate the way it can be implement.
<authentication mode="Forms">
<forms loginUrl="login page url" timeout="30"></forms>

</authentication>

Then you should show the location which need to be restricted from anonymous users.
After the <system.web/> tag we can write following code to above purpose. It's pretty cool, isn't it..?

<location path="FolderNameAuthenticationNeed" allowOverride="true"> <system.web>
<authorization> <deny users="?"/>
</authorization> </system.web> </location>