Have a look into the XML file of your asset. You will have to edit such with a Text Editor like Notepad. If you require information of how to do that, load a template into your Editor of a building that has a similar function as what you like to achieve. Save that and check the resulting XML file.
Using that process, i modified the function of the new asset plus i added further objects from other template buildings into my assets and positioned them with the Editor.
There is no easy to use graphical interface for this - you have to get into the XML files.

The resources.xml is all about the cost of buying and selling resources. My question was, when you create an asset in the editor, how to make it uses a raw material to produce a good? In the editor, it does not give you this option.

Check the game's ../Steam/steamapps/common/City Next/CityNext/Data/xml/resources.xml

Can you make a guide how you made a functional huilding which needs raw materials? It will be useful to us to create more contents. Is it like copy some codes from an XML file to others and edit?

Yes. The last screenshot above gives you all the details.

It manufactures paint to use in textile?