Or via the UI: open the Extensions panel, click the ... menu, select "Install from VSIX", and choose the downloaded file.
Usage
To start a new workbench, use the command palette (open with Ctrl+Shift+P or Cmd+Shift+P) and run Workbench: Start.
This will start your default profile.
An indicator at the bottom right of the screen will show you the status of your workbench and a notification will pop up once it's ready.
You can connect to the compute node directly by clicking the "Connect" button in the notification.
Clicking the status bar will also will open a menu with options to connect and stop the workbench.