So I do it different probably since i don't use fish sauce - I don't think you can do it a wrong way (unless it begins to mold instead of ferment)
but here is how I do it (the lazy way)
cut the Napa in chunks, salt it (try not to use iodin salt) very heavy let it sit for a day with occasional stirring if you feel like it.
If the Napa goes from white to transparent and lost it's "crispness" that's when its done (not completely transparent of course :D) drain the water.
prepare your spicing
-Gochugaru (lots of it!)
-some fresh ginger
-Spring onion
-garlic
-Soysauce
mix with the napa let it sit
for aslong as you please.
this is the most basic version I do
always try different things
i'm interested to know as how you did yours :)