How to join a space
To join a public space
Click the + next to Spaces in the left-hand taskbar. This will open up the space creation dialogue. Click on the "Browse spaces" button.
This will open up a list of spaces you can join. Scroll down or type in the space name that you'd like to join.
When you've found the space that you want to join, click on it. You will then be added to the space.