To create a listing on Trade Me you simply need to map the product you want to list, to a category on Trade Me.
From the Dashboard, you will see the Products section - underneath the summary of total products you can see 'Reasons for not being listed'.
Under products that 'Need category mapping' - click 'Map Now'.
You can map single products or a whole category of products.
For more information on how to map products see Category Mapping.