Unfortunately, setting up a table to add/delete rows is not as simple as adding a button and *poof*, it works. There is scripting involved along with lots of trial-and-error.
First thing, please do reference the above mentioned link and read it thoroughly. It will also help to open this PDF with Designer to see how it is set up.
See:
http://www.adobe.com/devnet/livecycle/articles/AddingRemovingTableRows.pdf You'll need to set up your table and edit the script to accommodate your table info (i.e., the exact rows you have, what your rows and columns are named, etc.) You'll need to view your Script Editor to do this and the appropriate command (select the Click event). It is there that you can change the script.
Being savvy enough to understand and use scripts is a must when creating tables to add/delete rows and other such features.
Good luck - hope this helps.
