How do you.......

[sparklygirl522]

.....use a .nbz file? This is really new to me and I see people let you download those files , but I don't know what to do with them.

[Chewie]

/moved to Newsgroup section. More relevant.

[General2k]

If you do a search on google you will find lots of guides. For instance I searched for "nzb guide" (http://www.google.ca/search?hl=en&q=nzb+guide&btnG=Google+Search&meta=) and I got over 170,000 results.
Here is the first one that explains a bit.
http://docs.newzbin.com/Newzbin:NZB_Guide

Also Slyck has some good guides on this.
http://www.slyck.com/ng.php?page=9

[mata7]

.....use a .nbz file? This is really new to me and I see people let you download those files , but I don't know what to do with them.

if you don't want complicate you self, just download grabit, select load NBZ, you file will download automatic one be one

of course you need usernet server account