No worries, easy as pie, I followed a tutorial myself back in the day, I will try to write a quick one, I can tell you're confused about the Mask file.
A little tip. In CTU there are things called 'Tint Colour A, B, C + D' right? And in game these tints are represented by the colour pallet. What confused me back in the day was Masks as well: WTF were all these colours for? lol
Basically, each Tint is represented by a colour on the Mask.
Tint Colour A = RED
Tint Colour B = GREEN
Tint Colour C = BLUE
Tint Colour D = I can't remember lol I think it's like black or something.
But anyways, I don't do my masks in purple and yellow etc because it's too confusing (I only use those colours now because I understand how channels work). And that's rarely.
What I actually do is my Masks in RED, GREEN and BLUE only. No other colours at all. I make sure the colours are seperate.
I usually fill the background with RED. So everything responds in the game if I colour the MIDDLE Pallet (the middle pallet in the game is the same as Tint Colour A in CTU). I know I've lost you here but once I write the tutorial you'll understand. I'll go through things step by step to help you understand Masks. They are really complicated, as you can see lol
But anyways, I fill the background with RED, then do the highlights in GREEN. This means that the shadows are controlled by Tint Colour A (middle pallet) and the highlights of the eye are controlled by Tint Colour B (I think that's the bottom pallet when you have 2 colours).
Ok so basically most of my Contacts are only 2 colours to keep them simple, so I don't worry about putting any blue on my Mask.