It's a little hit-or-miss at the moment, and unreliable.
How I do it is:
- Search the community using its full name, e.g.
[!lemmy@lemmy.ml](/c/lemmy@lemmy.ml)
- It'll show up no result if the community hasn't been "encountered" by your instance before. If it has, it'll just show up here and you can subscribe to it.
- Search the name again, only this time just the first part, e.g.
lemmy
- The
[!lemmy@lemmy.ml](/c/lemmy@lemmy.ml)
instance should show up.
Basically the first time you search, your instance will go and download/cache the community for future users. For some reason though, the search seems to lag behind a little in showing it.