By default, the Organisations Landing Page gives you a choice of views, including:
My Organis ...
To designate an Organisation as a customer or supplier you must have been granted the right Capability by your System Administrator. (Relate own organisation CRM customer / CRM supplier respectively).
Once you've set up an Organisation as a Customer (via the Agreements checkboxes) you'll be able to view it and others in the Customers view on the Organisations Landing Page.
Transaction Documents are linked to the Customer Organisation, so remember to set up an Organisation as a Customer before you try to create Transaction documents for that record.
The Transaction documents are Quotations, Customer Orders, Invoices and Credit Notes.
Like Customers, Suppliers are configured in Workbooks by the Agreements checkboxes in an Organisation record. Once you've done this, you'll be able to view it and others in the Suppliers view on the Organisations Landing Page.
Transaction documents are linked to the Supplier Organisation, so remember to set up an Organisation as a Supplier before you try to create a Supplier Order for that Organisation.