Follow these steps to select the spatial data sources to which documents can be associated:
In the Extensions/Documents section, click on and then on Data sources to open the configuration wizard.
Click on to add a data source.
In the menu, select the Data source name and the Attribute name to use in order to establish the association between each element of the data source and the documents.
Click on Add to add the data source.
Click on to add other data sources.
Click on Save to save the data.