To add on to the person who commented before me, you say...:
안녕하십니까?
(Hello)
Pronounced: an-nyeong-ha-sim-ni-kka?
[It looks like it should be an-nyeong-sib-ni-kka but it's not, because the ㅂis pronounced like an 'm' for the sake of making it sound smoother when saying it.]
It is typically said to strangers that are older than you. It's more formal than 안녕하세요.
안녕!
(Hello)
Pronounced: an-nyeong!
It is typically said to greet you friends or people you are close to. It is less formal than 안녕하세요.
만나서 반갑습니다.
(Nice to meet you.)
Pronounced: man-na-seo ban-gab-seum-ni-da.
[Note that the ㅂ in 습 is pronounced like an 'm' to make the sentence/phrase flow more.]
It is a more formal/respectful way of saying "Nice to meet you" (만나서 반가워요).
For more details you should head over to this site: http://www.talktomeinkorean.com/
Hope I sort of helped? ^^
