Lock Alpha? Layers?

[CookieMonster3000]

I was browsing though the Oekaki, and trying to draw, but some things I didn't understand:

What is Lock Alpha? What does it do?
I don't understand how to use them layers, or what they do, or anything, really. It make (Photos or detailed instructions would be nice for this one.) This make it hard when I tried to colour in a editable Oekaki, but the layers confuzled me. I could delete a layer, but not undo that. In some layers I was drawing under the editable Oekaki, sometimes compleatly over it. I have no idea.
Lastly, what is a collab?

Thank you very much. :3

[Vampiric]

http://wiki.chickensmoothie.com/index.php/Oekaki_guide

Lock Alpha is for colouring in areas you already pre-coloured, so you can stay inside certain areas without having to clean up your colouring every time. You have to colour first, then tick lock-alpha, then colour will only appply on that layer in that area. (only works on the layer you have colour on)

Layers are simple. + makes a layer, - removes a layer. You can make lineart on a layer above the rest, then colour beneath it. Layers allow you to make changes without having to redo whole portions of your picture.

To undo, press undo or Ctrl+ Z.

To make sure you colour in the right layer of an editable, click on the layer below the lineart, or click on the very bottom layer then press +, and itll make a new transparent layer for you to colour on.

Collab is when someone draws part of a picture, then sets permission for the next person to then edit (aka add onto) the picture with some art of their own.

[CookieMonster3000]

Oh...
Thanks so much!
*Goes to draw editable*