There is no "how to" for PitBull layouts. And the mod structure is still changing as it keeps being developed. You just need to get your hands dirty. Look at the templates that are already there.
The one important thing to know is that anything which is not defined in your layout code takes on how ABF is set up. eg, you don't define how to display Health Text in your layout, it will be displayed that way the ABF does it.
You need to create your own Lua file to register the layout with PitBull. For your layout, I recommend looking at the Seerah layout that comes with PitBull, since it's the closest to what you're looking to do.
Yea... Seerah's is similar but still pretty far off, and looking in the layout file for that pretty much only has aura stuff, unless I missed the rest of it.
I think the main thing I need is some direction as to how to is:
Create a frame for things, such as cast bar
Location of things such as master looter, pvp icon, combat/rest icon, etc
The buffs/debuffs I can work on later, but the base layout is what I want to get first.
And there is no documentation or anything, anywhere for people that don't know ace/lua ? no code comments in a layout file somewhere or anything?
Seerah's layout only includes auras, name text, and class text, because those are the only things that are different from ABF. Everything else is the same as ABF, so it doesn't need to be specified in the layout.
You can look in the oUF layout for examples of how to customize the icons, starting with:
This code says that the raid target icon should be 20x20 and anchored by its center to the top center of the frame.
There's not really any documentation because it's all just standard WoW Lua. SetHeight, SetWidth, SetPoint, etc. are all functions that any addon can use to create and customize frames. They're not specific to PitBull layouts. Probably the easiest thing to do is draw your layout on paper, with boxes representing each element, and figure out how each element is positioned relative to the frame.
For example, if you wanted your name and class text inside the frame but above the health bar, you could anchor the top left of your name text to the top left of the unit frame, and then the top left of your health bar to the bottom left of your name text, and so on.