There are a couple of good samples for doing touch and drags and so on, in the MOAI sdk samples folder. The most enlightening sample is in "samples/input/input-picking", since this gives you the details on how to put things up on the screen, have them react to touch events, move when dragged, and so on. I highly recommend you check this sample out, its a very easy to understand mechanism and you will, probably, have a good time with it.
Then, when you've checked that out, have a look at the Hanappe framework. A lot of folks seem to go straight for the frameworks once they get rolling with MOAI - after all, MOAI is quite low-level in many ways, and the frameworks contributed by the MOAI hacker community are in many ways absolutely brilliant in their own light - but I would suggest you first learn how to do it the 'plain' MOAI way first (input-picking), and then look at Hanappe, because there is a lot to learn in the Hanappe framework, the docs are in Japanese, and you'll have to know how MOAI is doing things in order to properly 'grok' the code for Hanappe itself. Here is where Hanappe lives:https://github.com/makotok/Hanappe
In particular, look at the rpgmap example (at the bottom of the main samples list when you run the main.lua demo included in the framework) as it provides a very nice on-screen touch-control surface interface that might be exactly what you are looking for. Plus, there's the whole "everything you need to build an RPG and more" is included, thing.
Good luck, lets hear how you progress - and glad you got things happening!