Each page of your site is first inscribed on-chain as an Ordinal, which gives it a transaction ID (TXID). A Web3 Site is then simply a name plus a small map that links each page to its TXID. The pages themselves are ordinary, self-contained HTML files, so building one takes the same skills as building any simple website — the only difference is that the pages live on the blockchain rather than on a server.
We've also made a video that walks through the whole process: "Web3 Websites for Photographers, Artists and Musicians: Prove Authorship, License Your Work, Get Paid" (https://youtu.be/BSecAAF4QlI).
At the moment, Web3 sites on the BSV blockchain are viewed through https://browser.ordnet.io/. (Web3 domains can be bought at https://domains.ordnet.io/). Soon, you'll also be able to register your site here on BSV Search so people can browse it directly — the way we already display the Earth Log, Marquez and Thank You sites. Making these sites viewable in more than one place adds real resilience: your site, and everyone else's, stays findable and browsable even if any single browser goes away. We're working on this now, so it's worth checking back.