When you log-in to the Share3D dashboard you are taken to the Models homepage.
Once you have imported models from Sketchfab this page will show a preview of each. You can filter your list to see the models that you are adding metadata to and are not published, the models that are awaiting publication, and the published models.
To get started you need to choose which models in your Sketchfab account you want to work on in Share3D.
When you log in for the first time, if you are new to providing data to Europeana you will see a red button labelled "Sign DEA Agreement". You don't need to worry about this until later. The agreement is explained in the section on sharing your models with Europeana.