Hi, neither I knew how to use lua when I started to develop the game. First at all, you need to know at least one programming language (better if object oriented). Then, I suggest you to study from here:
https://www.lua.org/manual/5.1/
http://lua-users.org/wiki/ObjectOrientationTutorial
these are the things that I've done before start. Of course, for the rest you need to try by yourself, so start with some basic stuff like render a sprite, move into the screen, etc.
Every time you get stuck use google to get some help. That's all :)