Command Palette
The Command Palette is the main way to access actions in Zed. Its keybinding is one of the first shortcuts to learn: cmd-shift-p|ctrl-shift-p.

To try it, open the Command Palette and type new file. The command list should narrow to workspace: new file. Press Return to create a new buffer.
Any time you see instructions that include commands of the form zed: ... or editor: ... and so on that means you need to execute them in the Command Palette.