Day 1

はじめまして｡　こうじです｡    How do you do?    I am Koji.

どうぞよろしく｡    Pleased to meet you.

おはよう ございます｡　    Good morning./Hello.

こんにちは｡    Good afternoon./ Hello.

こんばんは｡    Good evening./Hello.

しつれいします｡    Good-bye. 

Literarily, this expression means "I am committing a rudeness."  It is often used for instructors or socially superiors.

さようなら｡    Good-bye.

This is a formal way of saying good-bye.  This might bring some sense that the speakers are not going to see each other for a while.

じゃあ，　また｡    See you later.

This is informal way of saying good-bye.