Perhaps you should consider learning "Pure" Lua first?
You may consider it much easier to transition to RBX.Lua if you begin with attempting to learn fundamental scripting/programming concepts standalone within the "regular" development environment.
Focus on experimenting with the concepts. Algorithms(Computer instructions) should not "tell" the computer of what task to perform, they should simply inform the computer of how to accomplish said tasks.
An interesting guide can be found below:
http://www.lua.org/pil/ |