So I decided I wanna share my knowledge of Japanese since I am currently taking a legitimate class in college at the moment :) so if you're not that interested, I have a funny gif for you to enjoy. (P.S. Spoodermun dances to any song, try it out!)
Lesson one: The Basics
Let's start with the simple "hello!" Everyone knows that you say "konnichiwa" to say hello, but there are multiple ways for different times of the day that would make more sense to use.
Good morning: おはよ[ございます]！/ Ohayo[gozaimasu]!
Good afternoon: こんにちわ！/ Konnichiwa!
Good evening: こんばんわ！/ Konbanwa
The sounds in brackets can be said but aren't always, depending on who you're talking to. If you're speaking to your friends or someone close to your age, you don't need the extra sounds. But if you're speaking to your elders or anyone older than you, to show respect, you would use the extra sounds.
Now for the ways to say good bye.
Goodbye: さよなら！/ Sayonara!
See ya: またね！/ Mata ne!
Good night: おやすみ[なさい]！/ Oyasumi[nasai]! (Again, the sound in the brackets doesn't always need to be used)
That is all for today! I hope you've learned something useful! Have fun telling your friends the different ways to say hello! And enjoy their confused faces ;)