This depends on the Text Editor / IDE and is a luxury feature. It’s not available in the built in Renoise text editor, I’ve not seen one decent one for Lua.
For example, I code in jEdit. It has a bunch of plugins to do the auto-replace and an exuberant ctags interface, but to get this all setup and working will take a newbie several days, and the results probably won’t be what you are expecting. You may have better luck with another editor.
@see: http://lua-users.org/wiki/LuaEditorSupport
That said you should not start this way. It’s like spending $500,000 on a home studio then saying “There! Now I’m ready to learn how to make music!” Stuff like this is only useful once you’ve paid your dues and know what is going on. There’s no easy way to learn to code.
You should look at Ledger’s sig which has links to beginners guides, and pick his brain if you can. He never coded before either. He has managed to script pretty cool stuff. None of his stuff is on the tools page because he’s a bit self conscious (?) but he’s kicking ass.
Good times.