This site is currently struggling to handle the amount of new users. I have already upgraded the server, but it will go down regardless if half of Reddit tries to join.
However Lemmy is federated software, meaning you can interact seamlessly with communities on other instances like beehaw.org or lemmy.one. The documentation explains in more detail how this works. Use the instance list to find one where you can register. Then use the Community Browser to find interesting communities. Paste the community url into the search field to follow it.
You can help other Reddit refugees by inviting them to the same Lemmy instance where you joined. This way we can spread the load across many different servers. And users with similar interests will end up together on the same instances. Others on the same instance can also automatically see posts from all the communities that you follow.
Edit: If you moderate a large subreddit, do not link your users directly to lemmy.ml in your announcements. That way the server will only go down sooner.
Is there a newbie guide written up already somewhere? This is exactly the sort of things it needs, which should be linked to new signups.
Documentation etc can be found from their github page
https://github.com/LemmyNet/lemmy
Sure it can be found there, but pointing newbies to github would be too demanding.
At the bottom of every page, there you find a link to the documentation pages.
Sure, its a bit wordy... lacking in images with step by step instructions. If I had time I'd put something together with screenshots and figure out git and submit a pull request... maybe eventually.