Whilst we tend to start with named colours and then move to RGB colours possibly in hex it is worth considering HSL, see On Switching from HEX & RGB to HSL — Sara Soueidan – Freelance-Front-End UI/UX Developer for some details. The key piece for me to learn is complimentary colours and that kind of thing.
If you need help with picking colours then Color picker tool | MDN from Mozilla should prove to be a very handy tool.