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.