First notebook entry: Introducing myself

Hi, how are you doing? 

Hi, how are you feeling? < 그렇지만 미국인으로서, 우리는 이렇게 말할하지 않아요.  
I'm here in Curitiba, Brazil. < 좋습니다.

I'm learnig Portuguese here. << 어떤 언어의를 위한 첫 글자를 항상 대문자로 써야 돼요.

I'll be back later.  I have to go to my class now.

그건대문자로써야합니다. 

바꿔쓸수있는표현은제가추천하는더자연스럽고일반적인방법의표현입니다.

오타, 또는수정이필요한부분그리고단어의순서, 단어의선택이나철자를고쳤습니다. 

밑줄이있을때는알맞은구두점과띄어쓰기를사용해주세요.

보라색이저의코멘트입니다.

------ (이것이도움이됐으면좋겠습니다)

I saw your thing about wanting to speak less formal English, more spoken/slang...

First notebook entry: Introducing myself

How are you feeling there.
I'm here in Curitiba, Brazil.

I'm learnig portuguese here.

I'll be back later, because I have my class now.

This entry is slightly awkward.. This is how someone would say it casually:

How are you?

I'm (Here) In Curitiba, Brazil.

I'm learning Poruguese here!

I'll be back later, I have to go to class.

What you wrote, is correct, but pretty awkward. Good job though!! :)

축하해요 ^^