Each Space is located along the left side of your Workspace as a circular icon. Folders and Lists are in turn displayed in the sidebar next to Spaces.
At first, it can be a bit daunting, but in practice it actually makes life much easier.
Once you start with structure, you'll always have it. And once you're used to it, you'll love it.
ClickUp's structure is outlined (from top to bottom) below:
Your Workspaces are the top level. You can join or create as many Workspaces as you like - and easily switch between them in ClickUp.
IMPORTANT NOTE: Each ClickUp Workspace is entirely separate, so it is not possible to view or transfer information between them. This is why most people prefer to keep everything all in one Workspace!
Spaces are the second level and allow all of ClickUp's customization. ClickUp makes it easy to switch between Spaces so you can have completely different workflows from Space to Space.
Try dragging and dropping your Spaces around in the sidebar in order from most to least used!
Folders & Lists
The sidebar also shows Folders and Lists. Basically, Folders group and organize your Lists of tasks. Folders are groups of Lists, which contain tasks.
While Lists do not have to be located within a Folder, every Task in ClickUp must be located within a List.
Lastly, this brings us to tasks, which are at the bottom of the hierarchy, but form the most important part of ClickUp. Tasks inherit traits from Spaces, and again, are located within a List. You can change where a task is located at any time, but if you want to change workflow settings (like Statuses, or Custom Fields) then you'll need to change them for the whole Space, Folder, or List.
Assigned Comments occur within tasks and List info. They work as action items that will notify an assigned user that a he our she is responsible for resolving a comment. Assigned comments provide a fool-proof way to never lose track of a task, as they will remain visible until resolved.
And of course, Subtasks are within parent tasks. A subtask carries the same traits as the parent task and Space that it is in. If your Space has Statuses and multiple assignees, your subtasks will as well.
Checklists are essentially simple, nested subtasks. Checklist items have the simplest statuses (either done or not done), and can easily be dragged and dropped between checklists.