If you dont put one in at all GB will make one when it needs to. If you want to add one you got from someone on here just put in GB folder yes.
Then when a new version of GB comes out make sure copy over the badnodes to new version folder before deleting old one.
Also something else to keep in mind is the format of the badnodes. For the US part of world it will look like
<bad_location><name>Obsidium Deposit</name><waypoint>4270.479 -3386.833 1021.632</waypoint><comment>Manual add</comment></bad_location>
And for people in EU side of planet will look like
<bad_location><name>Obsidium Deposit</name><waypoint>4270.479, -3386.833, 1021.632</waypoint><comment>Manual add</comment></bad_location>
Notice the commas
Good to keep in mind when adding badnodes posted on forums, and it just wont work for some reason. Check with badnodes added auto from GB to know which one for sure you need.