You can use all these codes.These notes are for beginners.
You should also check out html tutorials site like ;
Mozilla : https://developer.mozilla.org/en-US/docs/Web/HTML
Attribute list : https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes
HTML elements : https://developer.mozilla.org/en-US/docs/Web/HTML/Element
HTML Color Codes : https://html-color-codes.info/ also https://htmlcolorcodes.com/color-chart/ and also https://www.quackit.com/html/codes/color/html_color_chart.cfm
Sample Website Templates : https://www.quackit.com/html/templates/
HTML Tags and meanings : https://www.quackit.com/html_5/tags/ also https://learn-the-web.algonquindesign.ca/topics/html-semantics-cheat-sheet/
HTML Canvas : https://simon.html5.org/dump/html5-canvas-cheat-sheet.html also http://cheatsheetworld.com/programming/html5-canvas-cheat-sheet/
HTML Security and Browser Support Check : https://html5sec.org/
HTML Full codes : https://www.quackit.com/html/codes/