No web host "recognizes" nod files. A nod file is a database containing your site elements that Fusion uses internally.
When you publish, Fusion generates html files like any other web design program.
With a non-Netfirms version of Fusion, you can publish your site to Netfirms (although I'd find a new host if I were you) or any other web host.
Get Fusion XII, get a new host and you'll be fine.
We sell hosting at
www.awavedomains.com (GoDaddy reseller) or you can go anywhere for hosting.
Whoever at Netfirms is telling you this about nod files is clueless.