Finding your way around

From top to bottom:

Search opens the command palette (⌘K).
Today and Calendar, Sorus's own places.
Apps: the apps your extensions bring. The + beside the heading adds extensions.
Library: Pages, Objects and Types, and any apps you've pinned there.
At the foot: what you're doing now (see Activities), Trash, and your profile menu.

Jot isn't in the sidebar: it's where Sorus opens, and where every new tab starts.

Tabs

Each tab shows one place: Jot, a page, Objects, an app, and so on. ⌘T opens a new one; ⌘-click anything to open it in a new tab. See Tabs.

At the top of the sidebar, the workspace switcher shows which workspace you're in. Click it to switch or create one.

The menu at the foot of the sidebar holds quick appearance choices (light, dark, system; an accent color), Workspaces, and Settings (⌘,).