How to program a forum/chatting app...

[Kupot]

Hi Everyone!

So I've been scouring the internet and this forum but I haven't seen the answer to my question yet or something to explain how this process works.

Before I start, please understand, while I did look through almost 13 pages of results in the Dev 101 Forum, the search function was not working (I let it sit for about 30 minutes before going back and manually looking through each post) -- If I missed the post that explains the answer, please link to it and I'll post and conversate there. I apologize in advance if there is a duplicate.

So - my question is this: Simply put, all I want are users to be able to post text below a picture (think G+ or FB picture comments). Users should be able to see the previous posts as well.

A component to my android app that I'm creating should allow users that are logged into the app to talk. But I dont know how this is typically done to allow the interchange of information. I got the whim to build a server to bounce REST requests off of a domain I'd build there to handle the requests. While this is fine and would normally work with a desktop application (the world of development that I come from), I'm wondering if there is a better (possibly simpler) way to approach this?

As I am new to the Android world of dev - please link any tutorials you think are notable on this subject. I'm not shy to spend the hours experimenting.