How do I find a community for a particular interest like ballet or gardening?

You can look at several places in the Fediverse. Let's start at home. At Friendica.

At the top you have the contacts button. With the people icon. One can look in 'the local directory' with the relevant keyword.

But it makes sense to go directly to the global directory. You look a group about a specific topic. On what instance of Friendica it is hosted is not important.

Click on the entry 'Global directory' in the contacts section. It opens in a new window at an external website.

There you can search. You will notice the number of lists is relative modest at present. These are user and groups from many different Friendica installations.

At present nothing can be found about 'ballet'. We do have one match for 'gardening'.
dir.friendica.social/search/gr…

There is a button present to 'follow'. - That button does not work. Just click on the group listing itself.

There you find a button to 'follow' that works. Note the address in the address bar. You are now on an other instance of Friendica.

You get a screen to enter your Friendica handle. Enter it like it is listed on your profile page. And then you get the option to actually submit the request to join that group.

If the group you wish to join is not public you will have to wait to get approved.

The groups you have joined show up in the left side menu when you click on the 'network' button, what is the most left top button, the square.

Even if you have found a on-topic group that does not mean you will be happy with it. The 'gardening group' we found 'gardensplantshorti@squeet.me' has only a six posts and are 6 year old. - But you do have now a place to try to revive it.

If you can not find what you are looking for (and not directly interested in just creating a group yourself) looking at Lemmy makes most sense. Lemmy is presented as the Fediverse version of Reddit.

Friendica.world has a Lemmy sister at lemmy.world

There is the option to do a search in the community, including 'All'. Also nothing about 'ballet'. There are a fair bit of options related to 'gardening'.

While not a place with 'active buzz' the group gardening@lemmy.world is clearly the most mature.

Again, also that button there to subscribe does not work. You do the name of the group. And when you have the name you can go here at this Friendica instance and go to 'contacts' section. And enter that name of the Lemmy group via the 'add new contact' option.

That way you can just add a Lemmy group to Friendica.

Mastadon is the more mature pillar of the Fediverse . Most users.

I am not sure how it works there with groups. I think there is some group function also at Mastodon. In any case there is fair chance you will find users posting about the topic you are interested in.

And if you find those then you can also add those here. 'Contact' & 'Add new contact'.

This was intended that this also could be used as general help text. I do not think this ended up to be very useful. - I let you decide @Ruud of can do anything with this.