This is where you can find.. most of the stuff ive used on and for my site. Ill try find sources to everything but my success isnt guaranteed
General coding stuff
W3 schools - this is where you can find litteraly everything related to coding, not just html. If you know nothing i highly recommend this to be your starting point
layout builder - helped me a LOT starting out with understanding how layouts work and how to make stuff
sadgrl - just sadgrls site in general has many many resources
status cafe on a free site - this lovely person has created a widget for us free sites so we can use things that need external javascript, like the status cafe you can see on my home site, but she has widgets for other stuff too and also some coding tips so i would highly recommend you check her out!
Desing
tiled backgrounds - i dont use repeating backgrounds that often but they are great and sadgrl has a LOOOT you can choose from
free cursors - where i get all of my cursors from
favicon - you can get free favicons here or you can make one on your own!
melons gif printer - melon has a printer where you can get all kinds of gifs and pixel art and whatnot, you can repeatedly click random or you can type in a word and it will find items related to that word! hadnt used it yet but i already got soooo many things from there its great