ok so the shading part when you shade it the part should get darker and darker with the same color. like how you used red, the red should get a bit darker but not too dark so it will still look like its solid, if that makes sense. and at the last bit of the shading you should add a low opacity of black and shade the last bit of it the highlighting i would make it light but not too light unless theres a strong light shining over it (like a natural light or something) and depending if its shiny you add a glare to it(or add white streaks). the color should be lighter the more towards the light it is, like how you used red, it would turn lighter towards a reddish pink and so on what i do when i have to mix colors is i find a color kinda in between the two colors so it looks like its blending together, and then draw the color right where the two colors(that you need to blend) meet i hope this helped and that its not too complicated, im bad at explaining things and i talk too much -w-

youre welcome!!