The reason no reference projects are showing up in the Reference Projects window in ShipWeight (opens when selecting menu Database | Reference Projects... or Estimate | Reference Projects..) is that there are no projects registred in the project table in the historical database. How to export project data to the Historical Database is described in webhelp.
It might be that the wrong Historical Database is connected to ShipWeight. How to change Historical Database is described in webhelp and in the tutorial.