The Load Template command loads in the think3 application the original model of the part used to generate the selected part family.

You can find this command in the context menu that displays when right-clicking on a catalog in the catalog tree frame of the Catalog Browser; it is also present in the context menu of the Catalog Manager if you select a part family that you created on your own.
Your thinkPLM administrator may have disabled this function for your thinkPLM account, role or group.

The command opens a dialog that lists all the representation templates defined for the selected catalog; by double-clicking on one of the templates, you open the document in the think3 application and are enabled to modify it. Simply Save the file after modifying it to update the thinkparts catalog template.