There are three main things that you must know about your website SEO:
1. A technical part
2. Content
3. Link building (Use Linkreserchtools if you haven't got a clue what links are good for your site)
Check out this thread from Blackhatworld on how to create content, etc --
https://www.blackhatworld.com/seo/guide-full-example-of-how-to-do-on-page-seo.1251425/It's from 2020, but still worth checking out.