Switching to pages (and blogs) to Gutenberg

Hello,

I want to swtich my pages over to Gutenberg. How do I do this?

Do I have to create new pages and delete the old ones?

At the moment if I go into a page, say my about page, and click edit. There is a light grey Gutenberg button under the page title. However, if I click on it, it doesn’t give me blocks but code.

Is there a tutorial on this? Is there something I’m missing/not understanding about switching to Gutenberg.

I’m having a similar issue with my blogs, where I can’t seem to convert from classic editor to gutenberg.

Thanks.