"Ohayou Gozaimasu," and "Ohayou" are the Japanese ways to say "Good Morning."People who haven't actually studied the language usually end up spelling it some nooby way like. ohayo-gozimus!!!!!!!11111
It's pronounced like this: Oh-high-yoh, Go-zai-moss. >o work with me!

:o but it's not your fault. I did it too. XD

But yeah. It's a formal way to say, "Good Morning!"
"Ohayou!" Is informal; Usually used between friends. Saying this to a teacher, for example, is often considered very rude and disrespectful. It's kindof like calling an by their first name, in the English language.
Praise me and my semi-bilingual skills. >=O
Kthx.