To add a new workspace, navigate your account settings, and choose Workspaces from the drop-down menu in the upper-right corner.
Click on the Create New Workspace button. You’ll see a popup window where you should enter a new workspace name. Once you’re done, click the CREATE AND GO TO BILLING button. You’ll be taken to the billing tab of the new workspace.
Keep in mind, that workspaces are billed separately so make sure you really need one. If you need an overview of workspaces, read this.