Bild an iPhone application that communicate with server

[ginopiolo]

Hi everybody,
I'm sorry to create an other thread talking about communication between iPhone and server but I don't find any complete answer in the other threads.
Than, I'd like to create an app in which I've to exchange lots of simple informations,such as short texts,and I don't have some knowledges. I hope you'll give me.

I've an idea: in the iPhone I write code in objective-C, here I use the Json library methods to make requests sent to the server, now in the server I riceve the information with a PHP page, that is able to understand the requests and communicate with the central database, than processes the information and sent them back to the iPhone. Than please explain me if my idea is wrong, where it's wrong and what is the right way to follow.

In particular I dont know how the server communicate with the iPhone.

Please give me complete answers, explain me the basis of what I'd like to know, and tell me where I can find more information about!

Thanks everybody!!! :-)