Blanch the spinach by cooking it in boiling water for about 1 minute before removing it to a bowl filled with ice water. Squeeze all liquid from the spinach and set aside.
In the bowl of a food processor, combine the flours, salt, and spinach.
With the food processor running, add the eggs one at a time and blend until a coarse dough begins to form.
Remove the dough to a lightly floured work surface.
Knead until the dough is even throughout and somewhat elastic. The dough should be very tough and on the verge of difficult to manipulate. Add flour as needed.
Process the dough in small batches through your pasta maker according to the instructions.
Note: It is during this step that you will run the pasta through the pasta press numerous times, folding it in on itself and adding a little flour each time, to build the structure in the dough. I suggest doing this 5 or so times before rolling the pasta out in increments to get it to the appropriate thickness.
Once the pasta is rolled to the appropriate thinness depending on the type of pasta you are making, lay it out on a lightly dusted surface and cut out the shapes for the pasta you are making (for ravioli, farfalle, and other broad pastas). For pastas like cappellini, spaghetti, or fettuccine, use the appropriate attachments on your pasta maker or a sharp paring knife.
To sore, wrap pasta in a barely-damp paper towel, and the paper-towel wrapped pasta in parchment paper. Keep the pasta in the refrigerator for up to 3 days. You can also freeze the pasta in an airtight container and store for up to a month.
Depending on the thickness and shape, cook the pasta in boiling water for 2-5 minutes, or until al dente.