If you really want your printer to print your document on green paper, then you can visualize this with Scribus:
Open your document in Scribus
File > Document Setup > Display > Colors (at tab) > Fill Color
Now in the window, select a color that corresponds to your paper. Now click OK or Apply.
Now - just on your screen - Scribus will show you how the printed result will look.
This is only an approximation, unless your workplace has got a calibrated screen and your printer has provided you with precise detail about his setup and the paper for your order. You can improve the simulation on your screen like this:
File > Document Setup > Color Management > tick Activate Color Management and fill in all the detail that you know about your own system and about the printer.
You also asked this in a comment:
Thanks. According to this, we have the interesting situation that if I
place an order with, say, a green paper, any white in my document will
stay as green. If I tell the printing service that I want white to be
printed (because maybe some of my images have some white), the problem
will be that both the white in the images and the white in the
background will print. How can the printing service distinguish
between white meant to be transparent and white meant to be white? For
that we have another color: transparent. But according to the answers
here, scribus does not have it. Any solution?
No, I do not know an affordable solution: If you opt for green paper (which is exeptional, if you want photos printed on it), then indeed, any white parts of any content (parts of photos) will not receive any ink and will show paper-green.
You can define (pay for) a spot-color and tweak your document to have white ink applied but that would almost re-invent printing. You should rather opt for the classical approach and order white paper and print "green" on any area that you consider to be background. That would turn out cheaper I believe.
You mentioned special, structured, paper. My advise would be to concentrate on finding that quality of paper in white, rather than trying for exotic workflow which will be expensive and potentially frustrating to you and your printer.