In the BUilder, open the surface structure. Drag and drop your molecule configuration from the Stash to the surface structure.
FInally, use the
Move toll or other coordinate tools to place you molecule in the desired position.
If you do not find a configuration in the internal database you can search in some online database, e.g chemspider, and download the correspondent file (usually cif format).
then import it in the Builder form the "Add-> from file" option