I think this is one of the better explanations of Flexbox I’ve seen. I really helps you get a clear concept of how the basics work (which isn’t generally easy, I’ve found).
https://medium.freecodecamp.com/an-animated-guide-to-flexbox-d280cf6afc35#.gxcay1hnm
Feel free to discuss it here, or ask about things you still don’t understand.
Hopefully they’ll do one for CSS grid too. But short of that, Rachel Andrew has a great series of tutorials on her Grid by example site.
