Open your Workspace settings by right-clicking on the Workspace name in your channel tree, or by hovering the cursor over the Workspace name and clicking on the 3-dot button that appears immediately to the right of the Workspace name.
Set up your Workspace according to your needs:
Create New folders or channels right under your Workspace;
Sort Subchannels alphabetically, by creation date, by activity or manually;
Invite new members to your Workspace;
Manage members: assign Administrator role to a user, or deactivate users;
Mute a Workspace to stop getting notifications (the message counter will continue to display an unread message count, but alerts will be disabled);
Edit a Workspace name using Workspace “Settings”;
Mark All Read to clear the unread message indicator with one click;
Expand or collapse your Workspace to show or hide your Workspace channel tree;
Close to leave a Workspace.