Technology stack problem(jquery,struts,spring,hibernate)

Hi guys
I am trying to build a a social networking website (like facebook pretty much) but i am very new in IT world.I want to keep the front end and the back end as two separate layers and any communication between them should be ajax driven.How do i do that? In other words i f keep those 2 layers separate (front end and back end) how do i establish communication using jquery like how the technology stack should be?I am familliar with html ,javascript,css,jquery,struts 2,spring ,hibernate.How do i integrate those technologies to acomplish the task (think of a site like facebook)?Or any different/better opinion from mine will be appreciated.Thank you in advance.

Sounds like you want your back-end to expose something like a RESTful web API that the client-side code can hit with jQuery-driven Ajax.

exactly... but i dont know how to do that...

One step at a time. First, I'd learn how to define and set up a RESTful web service and get that accomplished. Then you can learn how to use Ajax to send requests to that API.

But i am planning to start coding the front end first,Is it a good idea to integrate with dummy data?what kind of servers to use?For starting out do i really need to connect with the database?

I'd build the backend first. Otherwise, your front end has nothing to connect to.