Check out these resource to start learning:
p5.js website: https://p5js.org/
The Coding Train - one of the best channels on p5.js: https://www.youtube.com/channel/UCvjg...
A great book and website to learn p5: http://www.generative-gestaltung.de/2/
Template/Boilerplate to start with p5 in codepen: https://codepen.io/boilerplate/pen/pL...