There four different ways to search for NZB files:
1) Usenet Providers – some Usenet companies like Easynews have a built in search feature where you can find and download NZB files in an “all in one” service.
2) Raw Search – websites like Binsearch.info will search Usenet and allow you to make an NZB file for anything it finds. You then need to use the NZB file with your separate Usenet provider.
3) Human Search – websites like NZBPlanet.net have a community of people who report the NZB files that they find. Since somebody examines the NZB before it is listed, you don’t have to worry about bad files that are spam or require passwords. You do need to have a separate Usenet provider though.
4) Newsgroup Search – you can go into newsgroups directly and see what NZB files are there by using a Usenet reader program like NewzToolz (free). This is not recommended for newbies. This method is suitable in a situation where the newsgroup you are interested in is so obscure that the NZB search websites are not indexing it.
There are numerous NZB search websites out there, with many coming and going constantly. It isn’t necessary to try them all out however, because many of them use the same back-end engine to do their indexing – a program called newznab. And that’s a good place to start if you are looking to set-up your own NZB-indexing site.