ToME: the Tales of Maj'Eyal

First time poster, longtime fan.

I want to make a simple new class by mixing and matching preexisting talent trees.
I'd use Adventurer, but the Adventurer's 1.00 talent scores don't quite function the way that the talents are balanced for in their original class options. I want 1.30 mastery like a real player character! Plus it'd be nice to be properly limited, and to avoid sifting through the list of every single talent tree when it's time to level up.

I'd make my own Addon for it, but I know nothing of Lua. I know very little about programming in general.
Developer Mode hasn't worked out. The Ctrl+L screen suggests that if I want to run some code, just type it in, dummy. But I can't run before I can walk. Nothing I've tried returns anything.
Ctrl+A does a lot of things, but I don't see anything that would let me slap together a character class with anything resembling a user-friendly interface.
If I could locate the code for a class, I might be able to copy+paste my way to victory, but I haven't been able to even find those files. I'm a Steam player.

If the right answer here is making my own Addon, I'm going to need to find Square 0 before I can try out Square 1! I'd really appreciate some help.

Try unzipping an addon file or unzipping a .teac file. That might help a little.

Yeah grab the simplest possible addon you can find and unzip it, good starting point
Have a look at my simplistic demo that adds a simplistic class: http://te4.org/games/addons/tome/tourist

If you're looking to just mix together already existing talents into a new class, my Steamshaper addon does exactly that. You can download it here: http://te4.org/games/addons/tome/steamshaper.

To elaborate a bit on what Micbran and DarkGod said: after downloading the add on (or any other add on, for that matter), you can manually change the extension to .zip and then extract the files. This wiki page will give you a basic run down of how to get things set up. For the most part, you will just be editing text files. Dev mode if more for testing.

Overloads, superloads and hooks can be a little complicated if you're new at this, but for what you want to do you won't need to worry about overloads or superloads at all. You'll need a hook to load in your new class, but that's all. Feel free to make a copy of my add on after extracting it and make the changes you want. After renaming the folder and setting up your init file, mostly you will just need to change the talents that are listed in data\birth\classes\steamshaper.lua (which is just a text file).

For the most part, the names of talent trees as fairly intuitive, but there are a few that are not. For reference, you will probably want to make a copy of tome.team in programfiles\steam\steamapps\common\TalesMajEyal\game\modules . As with the add on, you can change the extension to .zip and extract the files.

That should give you a pretty good start. If you have any questions on the specifics, feel free to send me a PM. I'm not the greatest at this, but I got started by doing exactly what you are trying to do, so I'm on pretty firm footing there