Where can you do this?
From your 'Clients', to the right hand side, above your list of existing Clients, is a blue button that says 'Create a new Client' - click this to create a new Client.
From here, enter in a name and a contact email (this is the primary contact email for the Client), then press save.
You have now created your first Client.
To find out more information about Clients, click here.