In your steemit frontend profile page, if you are new to communities and have not joined any communities yet, when you click on the "Communities" tab you will be presented with the following screen with the message "Welcome! You don't have any subscriptions yet." and nothing else. It is, of course, confusing. Devs need to put a "Explore Communities" link on this page.

But, If you click on the Steemit logo (1), you will be taken to the Community page. When you click on "Explore Communities" tab you will be presented with the following screen where all the communities are listed and you can join/subscribe to any community you like (2) and/or you can create your own community (3). Cost of creating a community is 3 Steems.