Theres nothing to explain though, its just adding the new rthings you see compared to the old one xD but if your talking about basic stuff like light shading etc, you should search up a tutorial ment for that and not on a walkthrough
did you know in ms paint (i think you can still do it in newer versions) if you color with one color that isnt black, you can then use the eraser tool and right click with that color selected, then the color white selected in the other box, and then it magically makes only that color disappear. It's saved me so much time on the rare occasion i decide to use paint
It's not just to make it disappear. You can also use it to change a colour whenever you want. For example, if you make the markings one colour, but like it a different colour, you can choose the original colour in the first box, then the colour you want in the second box. The second thing you can use this for is to add details inside a specific colour you want. For example, if you colour the body purple, and the tail blue, you can add markings to just the tail by using the eraser like you said.
Another trick is that you can hold down the Ctrl button and the + or - sign on the keypad to make your eraser bigger/smaller than the sizes they give you. That way you can add details or change a colour quickly. c: