１．Indicates a supposition and result: "If...then."
NOTE: Nara is often used after nouns. It is similar to -ba, -tara, and to.
Watashi wa gogo nara hima ga arimasu yo.
If it's in the afternoon, I'm free.
「I'll be free in the afternoon.」
Ashita ame nara, gorufu ni ikanai tsumori desu.
Tomorrow, if it's raining, I don't intend to go golfing.
「I don't plan to go golfing tomorrow if it rains.」
Ano hito ga iku nara, watashi wa ikitaku nai desu ne.
If she's going, I sure don't want to.
NOTE: A major difference between nara and -tara is that the clause after nara emphasizes what would (definitely) take place if the supposed even were to occur, whereas the result clause after -tara emphasizes what would "happen to" take place.
Noru nara nomu na. Nondara noru na.
If you [are going to] drive, don't drink. If you have been drinking, don't drive.
２．Indicates that a topic is being brought up: "as for."
Sono mondai nara, mō kaiketsu shimashita.
As for that problem, It had already been settled.
Waka no sankō-sho nara, Sasaki-sensei no kenkyū-shitsu ni aru.
If it's reference books on waka [that you're looking for], they're in Professor Sasaki's office.
Hope this helps!
°˖ ✧◝(○ ヮ ○)◜✧˖ °こゆうきあいはら°˖ ✧◝(○ ヮ ○)◜✧˖ °