Ajax in-line editing, saves to server

Really simple: I need to have pages that contain a 4 by 4 table. I can create those manually, that's fine. Inside each page there will be a table with 4 cells, and each cell will have an ADD/EDIT button. When user clicks on ADD/EDIT, they can add/edit or create new text that will live inside those tables. That text gets saved in a database somewhere... And this is all done within the same page (i.e., no new pages loaded - I believe this is called in-line editing and can be done with Ajax) See attachment for more details, but that's pretty much it.